Delayed Breast Cancer Detection in an Asian Country (Taiwan) with Low COVID-19 Incidence

Figures & data

Figure 1 Monthly trend in the number of breast biopsy procedures and breast cancer cases in the periods of 2019 (Pre-COVID-19) and 2020 (COVID-19). A reference map shows a total number of confirmed COVID-19 cases (including imported and indigenous cases) in Taiwan by months.

Table 1 Clinical Characteristic of Breast Biopsy Lesions, Percentage Change and Significance of Monthly Difference During Pre-COVID-19 in 2019 (N=477) and COVID-19 in 2020 (N=398)

	2019 (Jan-Jul)	2020 (Jan-Jul)	Percentage Change^a	Monthly Difference^b
	N	N	%	P value
Total biopsy lesion	477	398	−17%	0.03*
Patient Age (years)
≤ 50	223	178	−20%	0.09
> 50	207	177	−14%	0.32
Biopsy method
Mammography	128	98	−23%	0.04*
Ultrasound	349	300	−14%	0.10
Biopsy result
Benign	349	283	−19%	<0.01**
Cancer	128	115	−10%	0.52
Cancer pathology
Invasive	89	94	6%	0.62
Non-invasive	39	21	−46%	0.06

Notes: ^aPercent change between Pre-COVID-19 and COVID-19 was calculated by subtracting the case count in 2019 from the same study period in 2020 and dividing by the case count from 2019. ^bPaired t-test for monthly difference between pre-CVOID-19 (2019) and COVID-19 (2020). Variables of Significance (*p ≤ 0.05, **p ≤ 0.01).

Table 2 Cross-Tabulation of Monthly Breast Biopsy Pathology and Monthly New COVID-19 Cases During 2019 (N=477) and 2020 (N=398)

Month	New COVID-19 Cases	Total Biopsy		Monthly Percentage Difference^a			Phi Coefficient^b
		2019	2020	Total	Breast Cancer	Benign
Jan^c	10	23	13	−43%	−60%	−39%	−0.07
Feb^d	29	55	60	9%	15%	7%	0.01
Mar	283	80	52	−35%	−48%	−27%	−0.08
Apr	107	71	52	−27%	−29%	−26%	−0.01
May	13	82	72	−12%	4%	−16%	0.03
Jun	4	81	76	−6%	33%	−14%	0.08
Jul	20	85	73	−14%	32%	−27%	0.13

Notes: ^aThe absolute monthly difference (2020 minus 2019) divided by the value of 2019. ^bPhi-correlation coefficients between malignancy in breast biopsy and new COVID-19 cases in each corresponding month of 2019 and 2020. Phi coefficients of 0.05, 0.10 and 0.15 can be considered as weak, moderate and strong association between groups, respectively. ^cOnly January 21–31 of 2019 and 2020 included. The 2020 Chinese Lunar New Year holiday (January 23–29) coincided with the start of the COVID-19 pandemic. ^d Chinese Lunar New Year holiday 2019 fell in February.

Figure 2 Correlation between new monthly COVID-19 cases (N=466) and monthly difference of confirmed breast cancer cases between 2019 (N=128) and 2020 (N=115).

Figure 3 Percentage change of the number in breast cancer staging categories (stage 0–4) from pre-COVID-19 to COVID-19.