LAUSR

Breast cancer is a type of cancer that starts in the breast tissue and can spread to other nearby tissues in addition to affecting the entire breast tissue (1). It is the most common cancer worldwide, causing extensive mortality and many complications (2-4). The incidence of breast cancer is globally increasing, especially in developing countries. Notably, about 6 million women with breast cancer were globally identified during 2008-2013 (5). More than 255 000 new cases of breast cancer occurred in the United States in 2017. Meanwhile, the annual incidence of breast cancer is 33 cases per 100 000 people in Iran, and the highest rate has occurred in Tehran, Isfahan, Yazd, Markazi, and Fars provinces (6). One of the concerns associated with breast cancer is its experience during pregnancy (7). Pregnancy-associated breast cancer refers to cancer that occurs during pregnancy, breastfeeding, or one year after delivery. It is the second most common cancer in pregnancy, which rarely occurs and does not cause many deaths (8, 9). Diagnostic and therapeutic interventions during this period are implemented with special considerations. Women with breast cancer are clearly at a more advanced stage of the disease during pregnancy and usually have a poorer prognosis (10,11). One of the major challenges in diagnosis and treatment during this period is maintaining a balance in the aggressive care of these patients and appropriate treatments to maintain the health of the fetus/ baby. Given that the occurrence of this cancer during pregnancy can have adverse effects on the health of the mother, the baby, and the fetus, the current study aimed to investigate the factors affecting the incidence of this type of cancer during pregnancy.