Is Friday leukemia a non-entity?

Most hematologists are familiar with a subgroup of acute leukemias (AL) that first present on a Friday.¹ Diagnostic and therapeutic efforts in caring for patients with AL are usually work-intensive procedures, and there are AL patients felt to present on a Friday afternoon, prompting an intense activity at the onset of the upcoming weekend. It is clear that all efforts at optimal processing of fresh material from AL blood and bone marrow in hospitals and study groups organizing multicenter clinical trials are mandatory regardless of the weekday.^1,2 In a group of 197 patients with newly diagnosed AL, Wilop et al.,¹ in Germany, reported that Friday was significantly overrepresented compared with admissions on other working days, thus supporting the gut feeling of hematologists around the world.¹ Wilop et al. speculate that this observation stems mainly from the health care system in which primary care physicians and health institutions not specializing in hematology elect to refer the AL patient with a weekend approaching.¹ It has also been speculated that it reflects the state of mind of the patients who struggle through work all week and as the weekend approaches relax and realize that they do not feel well and subsequently present themselves for care. It has also been seen that many of these patients do have a history of presenting to primary care clinicians on a number of occasions before finally being taken seriously. On the other hand, the Friday afternoon admission of a patient with a potential diagnosis of leukemia creates perceived delays in treatment initiation. Although generally not felt to affect prognosis, the effect of a few days delay in chemotherapy for patients with AL has not been fully investigated. Wahl et al.³ were unable to demonstrate a significant effect of delay in chemotherapy initiation for patients with newly diagnosed ALL on the examined outcome variables.

In a group of 675 consecutive patients with newly diagnosed AL (both myeloblastic and lymphoblastic) presenting in the Centro de Hematología y Medicina Interna of the Clinica RUIZ, in Puebla, México in a 30-year period, we have found that Friday leukemia represents 16% of the cases of AL and that the weekday distribution of the AL cases occurred randomly (see Fig. 1). It is clear that the presentation of AL on Saturday or Sunday was significantly lower than on Monday through Friday (P < 0.001, χ² test) because on these days only emergency patients are received; however, the differences in Monday to Friday presentation of AL patients are not significant (P = 0.06, χ² test).

Figure 1. Weekday distribution of AL cases

Accordingly, our data do not support the observation of Wilop et al.¹ in a smaller group of myelogenous AL patients, in Germany. Several differences that could account for this discrepancy can be mentioned: they included only myeloblastic leukemias and we included both myeloblastic and lymphoblastic, and they recruited patients from a university hospital whereas we recruited them from the private practice. It is interesting to mention that in our analysis, there is no difference in Monday to Friday presentation of either lymphoblastic (n = 432) or myeloblastic (n = 243) leukemias.

Be that as it may, our data suggest that Friday leukemia is a non-entity that probably should not be added to the continuous revisions of the World Health Organization classification of Tumors of Hematopoietic and Lymphoid Tissues.⁴