The incidence of trismus and long-term impact on health-related quality of life in patients with head and neck cancer

Abstract

Background. Trismus is a common symptom related to the treatment of head and neck (H&N) cancer. To date there are few prospective studies regarding the incidence of trismus and the patients’ experience of trismus in daily life activities. The aim of the study was to assess the incidence of trismus in H&N cancer patients and the impact on health-related quality of life (HRQL), by evaluating the patients before and after oncological treatment. Material and methods. We used the criteria for trismus of maximum interincisal opening (MIO) ≤ 35 mm and measured the patients at several occasions before and after treatment during one year. The patients answered the HRQL questionnaires EORTC QLQ C30, EORTC QLQ H&N 35, Gothenburg Trismus Questionnaire (GTQ) and the Hospital Anxiety and Depression Scale (HADS). Results. The incidence of trismus was 9% pre-treatment and 28% at the one-year follow-up post-treatment. The highest incidence, 38%, was found six months post-treatment. Patients with tumours of the tonsils were most prone to develop trismus. Patients with trismus reported greater HRQL impairments with regard to the GTQ domains; mouth opening (p < 0.001), jaw-related problems (p < 0.05), eating limitations (p < 0.05) and muscular tension (p < 0.001) six months post-treatment. EORTC QLQ H&N 35 scores indicated clinically significantly more problems with dry mouth, swallowing and pain for patients with trismus, 6–12 months post-treatment. Furthermore, all patients reported pain, anxiety and depression pre- and post-treatment. Conclusion. The incidence of trismus in patients with H&N cancer is non-negligible. Trismus severely impairs HRQL and negatively affects daily life activities in patients with H&N cancer. Further studies regarding symptomatic treatment of patients with trismus are highly warranted. The symptom-specific questionnaire GTQ is useful to identify the problems in this group of patients given it is responsive to showing change over time.

According to the Swedish register of cancer, approximately 1300 persons in Sweden were diagnosed with cancer in the head and neck (H&N) region during 2010 [1]. Worldwide, the incidence of tumours of the lip and oral cavity alone was estimated to 263 900 new cases during 2008 [2]. In the H&N region, intricate anatomical structures carry out essential functions such as breathing, speech, smell, taste and swallowing. Tumour growth in this region, and the necessary treatment of H&N tumours, may impair these functions which leads to pain, oral dysfunction and negatively affects health-related quality of life (HRQL) [3,4].

The curative treatment of H&N tumours consists of radiation therapy, chemotherapy or surgery in different combinations. A symptom related to the treatment in H&N cancer, which previously has not been paid much attention to in the literature, is trismus. Trismus, restricted mouth opening, is a condition that for the single patient might result in great difficulties in daily life activities. Recent studies have shown that patients with trismus have persisting problems with pain, chewing and eating, dry mouth and lack of taste, all of which results in impaired HRQL [5,6].

Risk factors for developing trismus previously described are large tumour size, high radiotherapy dosage and tumour location, especially when located close to the muscles of mastication and the temporomandibular joint [7,8]. The most common cause of oncology-related trismus is radiation-induced fibrosis, while post-surgical scarring may also play a role [9]. The percentages of trismus in H&N cancer patients reported in the literature vary, and a recently published study including 69 patients by Johnson et al. revealed a high incidence of trismus (42%) [7]. Furthermore, the study indicated that poor physical function before the start of treatment and high external beam radiation therapy dosages (> 50 Gy) were related to significantly more trismus.

A systematic review investigating the incidence of trismus revealed a weighted prevalence for trismus of 25.4% for conventional radiotherapy and 5% for intensity modulated radiotherapy (IMRT) [10]. To date, there are few prospective studies that can confirm these results.

In spite of the development of new treatment regimens with higher doses of radiotherapy, accelerated and hyperfractionated radiotherapy and concurrent chemoradiotherapy, the improvements in overall survival for H&N cancer have been modest [11]. As new treatment regimens are introduced in H&N cancer, that potentially improves the loco-regional control of the tumour, these regimes have also shown severe side effects that affects the patients HRQL and daily life activities [12,13]. Hence, it is of great importance that the focus on endpoints for clinical research is not only on survival but also on the patients’ experience and HRQL outcomes.

The aim of this study was to investigate the incidence of trismus prospectively and to analyse the impact on HRQL in patients undergoing treatment for H&N cancer. This study also investigated the symptom-specific instrument Gothenburg Trismus Questionnaire (GTQ) according to its responsiveness to change over time in H&N cancer patients.

Material and methods

The ethics board of Sahlgrenska University Hospital, Gothenburg, Sweden, approved this prospective study. Participants all gave their written informed consent to participate in the study.

Inclusion and exclusion criteria

During 2007 patients with a primary diagnosed H&N cancer referred to the Ear, Nose and Throat (ENT) clinic at Sahlgrenska University Hospital and presented at the weekly tumour board meeting were invited to take part in the study. All patients with H&N malignancies in five medical centres serving the region of Western Sweden were included in the study. The actual catchment area covers approximately one-fifth of the Swedish population (1.6 million inhabitants). Patients with tumour diagnosis not expected to develop trismus were excluded (i.e. oesophagus, the skin, the larynx and the hypopharynx).

Maximum interincisal opening (MIO) definition

The variation of incidence in earlier studies is most likely due to the different treatment regimens used, the different tumour sites involved, and the different criteria used to define trismus. In the present study, we used the trismus definition proposed by Dijkstra et al. [5], i.e. the cut-off criterion for trismus as MIO of 35 mm, which is generally nowadays regarded as gold standard [14,15].

Assessment

MIO was measured and sociodemographic and clinical data was collected (Table I). The patients’ performance was assessed using the Karnofsky performance index [16], and comorbidity, using the Adult Comorbidity Evaluation 27 (ACE-27) method – a widely used and validated method [17]. TNM-classification and tumour stage was retrieved according to the system of classification determined by International Union against Cancer (UICC) [18]. The given oncological treatment was noted and data of radiation dosages and chemotherapy cycles were collected.

Table I. Clinical characteristics.

	Study patients	Non-eligible	p-value
	n = 75	n = 34
Age Mean (range)	62 (35–86)	65 (47–86)	ns
Karnofsky index Mean (range)	98 (60–100)	88 (45–100)	< 0.0001
Gender	n (%)	n (%)
Male	45 (60)	20 (59)
Female	30 (40)	14 (41)	ns
Family situation
Married/Cohabitant	46 (64)	15 (44)
Living alone	26 (36)	19 (56)	0.05
Work
In active work	35 (51)	12 (37)
Unemployed	2 (3)	3 (9)
Retired	31 (46)	17 (53)	ns
Smoking
Non-smokers	53 (77)	29 (85)
Smoking	16 (23)	5 (15)	0.0001
Dysfagia
No dysfagia	68 (96)	22 (69)
Only semi solid food	2 (3)	5 (16)
Only pureed food	1 (1)	3 (9)
Only liquid food	0 (0)	2 (6)	0.0003
Comorbidity ACE 27
No comorbidity	34 (48)	6 (18)
Mild comorbidity	20 (28)	15 (44)
Moderate comorbidity	13 (18)	11 (32)
Severe comorbidity	4 (6)	2 (6)	0.03

ACE 27, Adult Comorbidity Evaluation 27.

Patient reported outcome (PRO)

During the study year, different PRO questionnaires were filled out before start of the oncological treatment (pre-treatment) and then at three, six and 12 months after the end of the oncological treatment (post-treatment). Before start of treatment, instruments were distributed to patients at the tumour conference and mailed-back. A mail-out/mail-back procedure was used for follow-up assessments. Non-responders were sent one separate reminder within two to three weeks.

Gothenburg Trismus Questionnaire (GTQ)

GTQ is a newly developed symptom-specific trismus questionnaire. GTQ was well-accepted by the patients, with satisfactory compliance and low rates of missing items and has shown good psychometric properties (validity and reliability) after item reduction [19]. The GTQ contains 21 items; with 13 items divided into the three domains: jaw-related problems (six items); eating limitation (four items); and muscular tension (three items). The remaining eight items are retained as single items. The domains and single items range from 0–100, where 100 indicate maximal amount of symptoms and 0 is equal to no symptoms. The questionnaire has a one-week recall period for the three domains. The GTQ is suggested, with its clear clinical relevance, to be used as a screening tool as well as an endpoint in intervention and jaw physiotherapy/rehabilitation studies.

EORTC QLQ C30 and EORTC QLQ H&N 35

The European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ C30) is a cancer-specific questionnaire that evaluates HRQL in cancer patients [20]. The questionnaires consist of five function scales, a global quality of life scale, three symptom scales and six single items, in total 30 questions that describe the patients’ symptoms and functional level during the prior week. To address additional symptoms associated specifically with H&N cancer and its treatment, a complementary 35-item module can be used, the EORTC QLQ-H&N35 [21]. Calculated scale scores range from 0–100. On the functioning scales and Global quality of life scales, a score of 100 represents maximum functioning, whereas on the symptom scales and single items, a score of 100 indicates the worst possible symptoms. A change in score over time of > 10 points could be interpreted as clinically significant.

Hospital Anxiety and Depression Scale (HADS)

The patients also completed the HADS which is used to detect mood disorders in patients with somatic comorbidity [22]. The HAD scale consists of 14 items on a four-point response scale ranging from 0–3. Seven items for depression and seven items for anxiety with a score range from 0–21. For each factor (anxiety or depression), the results are interpreted as follows: < 8 points indicates within normal range, 8–10 points indicates possible and > 10 points indicates probable anxiety or depression.

MIO measurement procedure

The criteria for trismus, suggested by Dijsktra et al. with a cut-off level for trismus at MIO ≤ 35 mm, was used. The MIO was measured using a ruler and was carried out with the patients seated in an upright position. MIO was measured as the distance between the edges of the incisors of the mandible and the maxilla. The patients were all measured at the time for inclusion and were then followed-up with new measurements at three, six and 12 months after the end of the oncological treatment.

Statistical methods

For comparison between groups, Fisher´s Exact test was used for dichotomous variables, Mantel-Haenszel's χ²-test was used for ordered categorical variables, χ²-test was used for non-ordered categorical variables and the Mann-Whitney U-test was used for continuous variables. Prediction of change in MIO, normally transformed, was also done by using a stepwise regression analysis. All significant variables in the first analyses were included as possible predictors in the stepwise regression analysis. All tests were two-tailed and conducted at 5% significance level.

Results

Patient characteristics

During the study year, 127 patients were diagnosed with primary H&N cancer tumours at the weekly tumour board meeting at the ENT department at Sahlgrenska University Hospital and matched the inclusion criteria (Figure 1). Eighteen patients died before the first follow-up measurement, i.e. three months after the end of their oncologic treatment (post-treatment). Another 34 patients were, for the following reasons, not eligible; Seven patients declined participation, five were not measured as they did not attend the tumour board meeting, nine secondary to poor general health, one due to dementia, four because of technical difficulties measuring MIO as the patients were edentulous or had dental prosthesis, and eight patients were not eligible for unspecified reasons. In total 75 patients were followed up. The clinical characteristics of study (eligible) and non-eligible patients are presented in Table I.

Figure 1. Study population flow chart with treatment regimens and patients lost to follow-up.

A statistically significant difference was found where the non-eligible patients had a higher comorbidity, lower Karnfosky index, and were more often living alone in comparison with the study group. However, more patients were smokers in the study-group (23%) compared to the non-eligible group (15%). Tumour location and classification for the study group is presented in Table II, where a tumour of the tonsil was the most frequently diagnosed H&N cancer (32%).

Table II. Tumour location, classification and treatment.

	Study patients n (%)
Tumour location
Salivary gland	10 (13)
Gingiva, buccal	6 (8)
Tonsil	24 (32)
Tongue, floor of mouth	15 (20)
Tumour colli, base of tongue, oropharynx	11 (15)
Sinus, nose	6 (8)
Other (lip, palate, epipharynx)	3 (4)
TNM-Tumour classification
T 0	5 (7)
T 1	13 (17)
T 2	29 (39)
T 3	9 (12)
T 4	18 (24)
Not able to classify	1 (1)
Stage group
I	9 (12)
II	20 (27)
III	16 (21)
IV	29 (39)
Not able to classify	1(1)
Total	75 (100)

Treatment regimes

The patients all received their surgical and oncological treatment at the Sahlgrenska University Hospital using the same protocols and regimes according to tumour location, size and stage. Overview of the treatment regimes is presented in Figure 1. The radiation therapy offered was ERT, interstitial radiation therapy (IRT) or a combination of both. Sixty-six patients (88%) received irradiation therapy in combination with chemotherapy or surgery. Out of these, 71% received a total dosage of > 50 Gy and 29% received < 50 Gy. The radiation dosage ranged from 40.8–72 Gy. Forty-one percent of the patients had IRT in addition to ERT with a dosage ranging from 2 Gy to 25 Gy. Chemotherapy was generally given as two cycles of cisplatin and 5-fluorouracil. Fourteen percent received IMRT.

Incidence of trismus

The incidence of trismus during the study year at the different measurement points were 9% pre-treatment and 33%, 38%, 28% at three, six and 12 month post-treatment, respectively, (Table III). At the 12-month post-treatment follow-up, 60 patients of the original 75 were available for evaluation (Figure 1). The incidence of trismus at the time of inclusion was 9% (seven patients) and was seen in four patients with a tumour in the tonsil, two patients with tumour colli and in one patient with oropharyngeal tumour. Trismus pre-treatment was secondary to affection of the temporomandibular joint and adjacent muscles by the tumour.

Table III. Incidence of trismus in different H&N cancer diagnoses.

	Pre-treatment n = 75	Post-treatment 3 month n = 75	Post-treatment 6 month n = 69	Post-treatment 12 month n = 60
Diagnose	n (%)	n (%)	n (%)	n (%)
Salivary gland	0 (0)	2 (20)	2 (22)	1 (14)
Gingival, bucca	0 (0)	2 (33)	1 (25)	1 (50)
Tonsil	4 (17)	11 (46)	9 (38)	6 (27)
Base of tongue, tumour colli, oropharynx	3 (27)	4 (36)	6 (55)	5 (50)
Tongue, floor of mouth	0 (0)	3 (20)	5 (38)	2 (17)
Sinus, nose	0 (0)	2 (33)	2 (33)	1 (20)
Other (lip, palate, epipharynx)	0 (0)	1 (33)	1 (50)	1 (50)
All diagnoses	7 (9)	25 (33)	26 (38)	17 (28)

Incidence of trismus [maximum interincisal opening (MIO) ≤ 35 mm] during first year of follow-up after end of oncological treatment.

Impact on health-related quality of life

GTQ.

During the study follow-up year the patients reported more symptoms post-treatment compared to pre-treatment data in all three GTQ domains (jaw-related problems, eating limitations and muscular tension); statistically significance according to Table IV.

Table IV. GTQ-score, mean value, 95% confidence interval (CI) for H&N cancer patients.

	Pre-treatment	Post-treatment 3 months	Post-treatment 6 months	Post-treatment 12 months
	Mean CI	Mean CI	Mean CI	Mean CI
GTQ time measurement
Jaw-related problems	12.7 7.8–17.6	28.5 *** 22.1–34.8	26.9 *** 20.3–33.5	26.1 *** 19.1–33.0
Eating limitations	22.1 11.7–32.5	33.8 ** 24.2–43.5	29.6 * 22.2–36.9	28.6 20.5–36.7
Muscular tension	8.3 5.1–11.5	13.3 *** 9.4–17.2	15.5 *** 11.2–19.9	15.7 *** 11.5–19.9
Facial pain
Facial pain right now	14.4 8.8–19.9	17.0 11.1–22.8	12.3 7.4–17.2	14.7 9.3–20.0
Facial pain when worst during last month (l m)	27.0 19.9–34.1	31.0 23.6–38.4	25.7 18.3–33.2	25.6 18.4–32.8
Facial pain average value (l m)	22.2 16.3–28.1	27.5 20.6–34.4	22.2 15.5–29.0	21.6 15.8–27.4
Facial pain interfering with social. leisure and family activities (l m)	8.7 4.0–13.4	13.0 7.0–18.9	9.2 4.8–13.7	7.1 3.2–11.1
Facial pain affecting ability to work (l m)	11.6 5.7–17.5	15.6 8.0–23.7	12.7 5.8–19.6	10.3 4.3–16.2
Limitation in opening mouth (LOM)	9.3 4.7–13.8	30.4 *** 23.8–37.0	31.6 *** 24.4–38.7	30.7 *** 23.4–38.0
LOM interfering with social. leisure and family activities (l m)	6.5 2.0–11.1	11.4 * 6.9–15.8	9.7 4.4–14.9	7.0 2.9–11.1
LOM affecting ability to work (l m)	6.6 1.9–11.4	10.3 3.9–16.6	10.5 4.4–16.7	7.9 2.7–13.1

GTQ, Gothenburg Trismus Questionnaire; H&N, head and neck; MIO, maximum interincisal opening.

Domains and single items range 0–100, where 100 indicate maximal amount of symptoms and 0 is equal to no symptoms.

* p < 0.05, **p < 0.01, *** p < 0.001. Statistical significant difference between patients with (MIO ≤ 35 mm) and without (MIO > 35 mm) trismus at the single evaluation time.

There was also a statistically significant increase in problems with restricted mouth opening [Limitation in Opening Mouth (LOM)], during the study year. Significantly more problems were found in the patients with trismus (MIO ≤ 35 mm) in the domains jaw-related problems and eating limitations when compared to the non-trismus patients at the different times of follow-up (Table V). As expected, the patients with trismus had significantly more problems with restricted mouth opening. The trismus patients had also more problems with their ability to work and attend leisure, social and family activities, which was related to their limited mouth opening.

Table V. GTQ–score, mean value, 95% confidence interval (CI) for H&N cancer patients with (MIO ≤ 35 mm) and without (> 35 mm) trismus.

	Pre-treatment		Post-treatment 3 months		Post-treatment 6 months		Post-treatment 12 months
	Mean CI		Mean CI		Mean CI		Mean CI
GTQ time of evaluation
MIO (mm)	≤ 35	> 35	≤ 35	> 35	≤ 35	> 35	≤ 35	> 35
N	7	68	25	50	26	43	17	43
Items
Jaw-related problems	35.7 * 9.6–61.8	10.3 5.7–14.9	38.7 * 26.9–50.5	22.5 15.5–29.6	35.3 * 22.2–48.4	21.3 13.8–28.9	36.8 20.0–53.5	21.3 14.0–28.6
Eating limitation	28.1 –12.1–68.3	21.3 9.9–32.7	44.2 * 29.0–59.5	26.8 14.2–39.3	39.8 * 26.0–53.7	22.6 13.9–31.3	42.7 * 24.6–60.8	21.9 13.3–30.5
Muscular tension	11.9 −2.8–26.6	7.9 4.6–11.3	11.5 4.7–18.3	14.4 9.5–19.2	18.3 11.2–25.3	12.6 7.4–17.8	21.9 12.9–30.9	12.9 8.2–17.7
Facial pain (FP)
Facial pain right now	28.6 3.9–53.3	12.8 7.2–18.5	21.4 9.9–33.0	14.4 7.6–21.1	14.2 5.3–23.0	10.0 3.9–16.1	15.6 3.7–27.5	13.4 7.3–19.6
Facial pain when worst last month (l m)	40.5 11.2–69.8	25.5 18.1–32.9	31.0 18.4–43.5	31.0 21.5–40.6	31.7 16.1–47.3	21.0 12.5–29.4	32.3 15.3–49.3	22.4 14.3–30.4
Facial pain average value (l m)	40.5 14.0–67.0	20.3 14.3–26.2	27.0 14.9–39.1	27.8 19.0–36.5	26.7 12.9–40.4	18.6 10.6–26.5	29.2 16.0–42.3	17.9 11.5–24.3
Facial pain interfering with social. leisure and family activities (l m)	8.3 −13.1–29.8	8.7 3.8–13.7	11.3 0.9–21.6	13.9 6.2–21.6	11.3 2.4–20.1	7.9 2.4–13.3	9.4 1.1–17.6	5.8 1.0–10.5
Facial pain affecting ability to work (l m)	0.0 NA	12.7 6.3–19.1	15.0 0.1–29.9	16.0 6.0–25.9	12.5 1.4–23.6	13.6 4.0–23.2	12.5 −2.1–27.1	9.0 2.4–15.5
Limitation in opening mouth (LOM)	37.5 ** −2.3–77.3	6.6 3.1–10.2	40.5 * 27.8–53.2	24.3 17.2–31.3	48.8 *** 36.5–61.0	22.9 15.0–30.8	51.6 *** 36.6–66.5	21.3 14.3–28.2
LOM interfering with social. leisure and family activities (l m)	17.9 * −4.1–39.9	5.2 0.6–9.9	13.1 4.6–21.6	10.3 5.0–15.6	13.8 * 5.7–21.8	7.9 0.4–15.3	12.5 1.6–23.4	3.8 0.3–7.2
LOM affecting ability to work (l m)	14.3 * −3.9–32.5	5.7 0.7–10.8	16.7 3.5–29.8	6.4 −0.3–13.1	12.5 2.8–22.2	10.0 1.4–18.6	15.6 * 0.34–30.9	3.8 −0.1–7.6

GTQ, Gothenburg Trismus Questionnaire; H&N, head and neck; MIO, maximum interincisal opening.

Domains and single items range 0–100 where 100 indicate maximal amount of symptoms and 0 is equal to no symptoms.

* p < 0.05. ** p < 0.01, *** p < 0.001. Statistical significant difference between patients with (MIO ≤ 35 mm) and without (MIO > 35 mm) trismus at the single evaluation time.

Symptoms of facial pain were reported among both trismus and the non-trismus patients, although the trismus patients indicated a higher level of symptoms during most of the follow-up period (non-significant).

EORTC QLQ-C30 and QLQ H&N 35

The greatest HRQL impairment was reported in both groups at the three-month follow-up, especially in the domains of role function and fatigue, and also on the single items of dyspnoea and appetite loss (Supplementary Table I, available online at http//www.informahealthcare.com). Patients with trismus reported more problems according to physical function, pain and appetite loss (clinically significant) at 12-months post-treatment compared to non-trismus patients.

In the EORTC QLQ H&N 35, high scores on the symptom scales of pain, swallowing, senses and social eating were reported at three-months post-treatment (Supplementary Table II, available online at http//www.informahealthcare.com). At the 12-month post-treatment follow-up the patients with trismus had more symptoms in most H&N 35 variables compared to the patients without trismus. The items giving the highest symptom scores in both patient groups during the follow-up period were problems with dry mouth and sticky saliva. As expected the trismus group reported great problems with mouth opening and clinically significant more problems also in the pain, social eating and sexuality domains at 12-month follow-up compared to the non-trismus group.

HADS

Pre-treatment, 24 patients (32%) [Trismus (T) n = 1, Non-trismus (NT) n = 23] were defined as having possible or probable anxiety disorder and 16 (22%) (T n = 0, NT n = 16) having possible or probable depression (Supplementary Table III, available online at http//www.informahealthcare.com). At the 12-month post-treatment follow-up nine patients (17%) (T n = 2, NT n = 7) had scores indicating probable or possible anxiety disorder and nine patients (15%) (T n = 3, NT n = 6) had scores indicating having probable or possible depression.

Multiple regression analysis

At the six-month follow-up a low MIO value (mm) was significantly correlated to painkillers in EORTC QLQ H&N 35 (p < 0.05), a higher (> 50 Gy) radiation dosage (p < 0.01) and low MIO at start of the study (p < 0.001).

Discussion

To date there is, according to our knowledge, only one prior study that has prospectively investigated the incidence of trismus and impact on HRQL in H&N cancer [6]. Although trismus has been recognised to have a large impact on HRQL the knowledge about these patients and the incidence of trismus is limited.

HRQL is affected not only by the cancer itself and its treatment, but also by other medical conditions. When investigating comorbidity we found that patients not included in this study (non-eligible) had a significantly higher comorbidity and higher age suggesting that the results of this study may be an underestimate of the severity in symptoms in the whole patient group. Knowing that smoking is a major risk factor for developing H&N malignancies we found it surprising that only 23% of the patients in this study addressed themselves as smokers. The low prevalence of smoking might be due to underreporting of the real smoking behaviour.

The highest incidence (38%) of trismus in our material was detected at six-month post-treatment. At the 12-month follow-up there was a decrease in the incidence (28%) that can partially be explained by the fact that some patients improved but also by the fact that several patients died during the first year of follow-up. There is also evidence that trismus evolves most rapidly during the first nine months after treatment and then stops progressing in most patients [23]. Two recent studies, using the same definition of trismus (MIO ≤ 35 mm), have presented post-treatment incidence rates of 42% and 79%, respectively [6,7]. The study by Lee et al. revealed an incidence of 47% pre-treatment and as high as 79% post-treatment [6]. However, the study by Lee et al. is not presented with detailed specifications of tumour locations and the study group consisted of patients undergoing primary surgery, making high incidence rates rather difficult to interpret as valid for all patients with H&N cancers.

The patients with cancer of the tonsils were the one most prone to develop trismus in our study and this group also constituted the largest diagnosis in our material. In larger material there is a possibility that other tumour locations also are at high risk of developing trismus. Other studies have suggested that oropharyngeal tumours and parotid gland tumours as a group are prone to develop restricted mouth opening [7,13].

The patients in this study were found to suffer from impaired HRQL both before and after receiving their oncological treatment and many patients reported symptoms and loss of function at the one-year follow-up. The observed HRQL impairments with regard to mouth opening and jaw-related problems, problems with dry mouth and swallowing, eating limitations, muscular tension and pain post-treatment are in accordance with the incidence of trismus, and congruent with results from other studies [12,13]. According to the GTQ, trismus not only affects eating and dental hygiene, because of the mechanical restricted mouth opening, but also social and family life as well as the ability to work. In the EORTC QLQ H&N 35, we found that the trismus patients reported more problems with pain than those without trismus, six- and 12-months post-treatment. Pain is often associated with depression, anxiety and insomnia. The pain itself, as well as the associated symptoms, affects the patient's daily life activities and results in impaired social and physical function. This negatively affects the patient's quality of life. In the present study the patients with H&N cancer reported problems with pain both pre- and post-treatment, especially at the three-month follow-up occasion. The pain, as well as the cancer diagnosis per se, might affect the prevalence of anxiety and depression in the study population.

The three-month follow-up occasion, where a symptom peak for all patients was found, corresponded in time to about six months after being diagnosed with cancer. Generally data from different studies on HRQL using the EORTC QLQ-C30 and H&N 35 are difficult to compare since the chosen occasions of evaluation are different for each study. We chose to evaluate the patients in accordance to when they finished their oncological treatment in order to get consistency in the results and a possibility to compare the patients. Compared to data from Bjordal et al. [24], who investigated HRQL in more than 350 H&N cancer patients during one year from diagnosis, the trismus patients in our study had more problems with pain, swallowing, opening mouth, social eating, dry mouth and sticky saliva than the H&N cancer patients in general. There was also a difference in the use of painkillers, where patients with trismus in our study used more painkillers than the H&N cancer patients in the previously mentioned study. Persisting problems with negatively affected Global QL in H&N cancer was also shown in a study by Epstein et al. where EORTC QLQ C30 was used [3].

Furthermore, it is not unexpected that mood disorders such as anxiety and depression are frequent in this group of patients, taking into account the deficits in HRQL that has already been mentioned. In our study we found that about one-third of the patients suffered from probable or possible anxiety and one-fifth of the patients from probable or possible depression at the time of diagnosis. At the three-month follow-up (i.e. approximately six months later) there were still one-fifth of the patients that filled the criteria for probable or possible depression or anxiety. These figures correspond well to what have earlier been shown in research on H&N cancer and mental distress using the HADS [25].

Clinical implications

Given that this study indicates that all patients have greater symptoms at the time three months post-treatment, it is important to be mindful of such outcomes during the management of H&N cancer patients. The results from this study also indicate that patients with trismus suffer from pain, which seems to persist, and that many of the patients with H&N cancer presented with high levels of anxiety at the time of diagnosis, suggesting an unmet need where improvements are required. In order to improve the patients’ daily life activities and HRQL, it is of utmost importance that H&N cancer and associated symptoms, such as mouth opening ability, pain, anxiety and depression are appropriately treated.

Furthermore, the GTQ, a newly developed symptom-specific trismus questionnaire, was found to be useful in clinical practice as an endpoint in this intervention and rehabilitation study. The GTQ instrument has previously shown to have good psychometrically qualities according to validity and reliability and the present study has now also documented the responsiveness of GTQ to change over time [19].

Study limitations

In order to analyse the risk factors for developing trismus, a larger sample size is needed. In the present study, tumours of the tonsils seem to be a risk factor for developing trismus but likely there are other high risk locations as well. Also, the answering of the questionnaires requires effort from patients and, as such, there is a risk that patients, with high comorbidity as well as morbidity due to the tumour, do not have the strength to respond.

Conclusion

Overall the incidence of trismus (MIO ≤ 35 mm) was high in our material; 38% of the patients had trismus six months after finishing their oncological treatment in this prospective study. Furthermore, we found that patients with trismus had more pain and greater negatively affected HRQL than patients without trismus. We also found the symptom-specific questionnaire GTQ responsive to identifying patients’ change over time.

Declaration of interest: This study was supported by the Swedish Cancer Society; the Research and Development Council, Västra Götaland (Sweden) County and the Medical Faculty of Gothenburg University Sweden. The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.