Is Season a Prognostic Factor in Breast Cancer?

Abstract

<b>Background:</b> Some studies have indicated an inverse relationship between cancer risk and sunlight exposure.Others have reported that the prognosis of some cancers such as prostate, colon, ovarian and non melanomaskin cancer, were affected by the season in which the cancer was diagnosed. In our study, we evaluated whetherseason is prognostic in Turkish patients with breast cancer. Materials and <br/><b>Methods</b>: A total of 517 patients fromKayseri Training and Research Hospital were analysed retrospectively. Patients were divided into 4 groupsaccording to season of cancer diagnosis: winter, spring, summer and autumn. The prognostic factors for diseasefree survival and overall survival were investigated. <br/><b>Results</b>: No significant differences were found amonggroups regarding prognostic factors overall. Only estrogen receptor status and lymphovascular invasion wereindependent prognostic factors (p=0.001 and p=0.001 respectively). We found significantly differences for meandisease free survival among groups (p=0.019). Winter group had better mean DFS while summer group hadworse DFS. Mean overall survival was similar in the four groups (p=0.637). <br/><b>Conclusions</b>: The season is not anindependent predictive factor. However, due to interaction with other factors, we think that the season of cancerdiagnosis is important for cancer prognosis.