Abstract
The effect of the month of diagnosis on survival was investigated in two series of unilateral invasive breast cancer, of which one comprised 95% of all such histologically diagnosed breast carcinomas in the city of Turku, Finland, in 1945 to 1965 (n = 401), and the other 94% of all such carcinomas diagnosed in 1980 to 1984 (n = 337). If the histological diagnosis was made in January, February, or August to October in 1945-65, or in July to September in 1980-84, mortality in breast cancer was greater than if the diagnosis was made during the rest of the year (P = 0.03 and 0.009, respectively). Cancers diagnosed during the unfavourable months had more tumour necrosis in both series, and higher mitotic count and larger tumour size in the 1945-65 series. The number of diagnosed cases was usually less than the median during the months associated with unfavourable prognosis. Hypotheses to explain the altering prognosis by the month of diagnosis include seasonal hormonal changes and social factors.
Highlights
The season of initial discovery of tumour has recently been described to be an independent variable predicting survival in breast cancer (Mason et al, 1990), and women who detect their breast cancer in spring or summer were found to have more favourable survival as compared with those detecting their tumour at other seasons of the year
In 1945 to 1965 survival was poorer if the diagnosis was made in January, February or August to October than during the rest of the year
Mortality in breast cancer was greater during these months among postmenopausal women (P = 0.02, n = 266), but not among the premenopausal ones (P = 0.90, n = 135, Figure 1)
Summary
During the time period from 1945 to 1965, 461 cases of female breast cancer were histologically diagnosed in the city of Turku in South-Western Finland. Twenty-two patients were treated elsewhere, were lost to follow-up, or had insufficient clinicopathologic data, and women with either intraductal (n = 15) or bilateral breast cancer (n = 23) were excluded, leaving 401 patients in the final analysis (95% of all women with histologically diagnosed, unilateral, and invasive breast cancer in the city of Turku in 1945 to 1965). According to data from the Finnish Cancer Registry 404 cases of female breast cancer were diagnosed in Turku in 1980 to 1984. When calculating survival by the month of diagnosis, diagnosis was considered to be made when the pathologist reported breast cancer.
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