title: The effect of seasonal differences on prognostic factors in Turkish patients with breast cancer.
abstract: Several studies have shown that solar light affects the prognosis of breast cancer. This effect is mostly associated with vitamin D. In-vitro studies showed that vitamin D analogs change the receptor expression in breast cancer cell lines. In our study, we studied the effect of solar light on prognostic factors of breast cancer. Patients with breast cancer from two different regions of Turkey were included in the study. These regions have different seasonal features and solar light exposures. Nine hundred and eighty-six patients were from the Akdeniz University Medical Faculty of Antalya region, and 463 patients were from the Kayseri Education and Research Hospital of Kayseri region. The Antalya region has warm climate and more solar light exposure. The Kayseri region has relatively colder climate and less solar light exposure. When histological features are considered, the estrogen and progesterone receptor expressions were higher in the Kayseri group, and a significant difference was observed for the progesterone receptor (P=0.013). No significant difference was observed for the estrogen receptor but a significant trend was observed (P=0.056). No significant difference was observed in CerbB2 expression between groups. There were significant differences for histological and nuclear grade (P<0.001 and P=0.002). The ratio of histological grade 3 was higher in the Kayseri group and the ratio of nuclear grade 1 was higher in the Antalya group. Our study showed that, due to seasonal differences, solar light exposure leads to significant changes in prognostic factors for breast cancer. This result may be interpreted as the reflection of in-vitro findings in a clinical setting and may be accepted as one of the first such reports in the literature.
authors.affiliation: Department of Medical Oncology, State of Educational and Research Hospital of the Govenment, Kayseri, Turkey. doktorhasanmutlu@gmail.com.tr
authors.forename: Hasan
authors.initials: H
authors.lastname: Mutlu
authors.forename: Taner
authors.initials: T
authors.lastname: Colak
authors.forename: Mustafa
authors.initials: M
authors.lastname: Ozdoğan
authors.forename: Yasemin
authors.initials: Y
authors.lastname: Altuner Torun
authors.forename: Zeki
authors.initials: Z
authors.lastname: Akça
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000208:ethnology* / Q000378:metabolism; D005260:Female; D006801:Humans; D008875:Middle Aged; D011379:Prognosis; D012621:Seasons; D013472:Sunlight; D014421:Turkey / Q000208:ethnology; D014807:Vitamin D / Q000378:metabolism
chemical_list: D014807:Vitamin D