Case Report Colorectal cancer and breast cancer: two cases with a review of literature

Multiple cancers may occur in an individual because of a genetic predisposition, environmental exposure, cancer therapy, or immunological deficiency. We presented two patients with two cancers in the West of Iran. Case 1: a 52-year-old woman referred to Clinic of Oncology (December 2010) with complaints of left breast lump with induration. The pathology report had shown invasive ductal carcinoma of left breast. Immunohistochemistry (IHC) report showed that ER, PR and p53 were positive, HER2 was 3+ and Ki67 was positive in 20% of tumoral cells and stage was T2N2Mx. After surgery, the patient was treated with chemotherapy regimen (dose and course epirubicin 150 mg combined with Endoxan 1000 mg for four weeks and then paclitaxel 300 mg every two weeks for four weeks. In July 2011, she was treated with radiotherapy for 25 courses (5000cGy/25 fractions). At the end of left breast irradiation, she received tamoxifen 20 mg/day. The CT scan of abdominopelvic in October 2013 showed a tumoral infiltrative process in the rectal area. Pathology report showed well-differentiated adenocarcinoma. The genetic laboratory reported KRAS mutation and NRAS wild-type. She was not eligible for targeted therapy with Cetuximab. Case 2: a 54-year-old woman referred to Our Clinic with complaints of abdominal pain on January 30, 2012. Pathology and IHC report had shown with well-differentiated Adenocarcinoma of left colon. The patient was treated with chemoradiation. The patient was treated with chemoradiation. In May 2014, mammography showed a medium to high density lesion in the left breast. The pathology report showed invasive ductal carcinoma. She was treated with docetaxel 140 mg/day and epirubicin 150 mg/day. In her past history, she had two sisters with the diagnosis of breast cancer. In conclusion, there is a correlation between breast cancer and colorectal cancer genetically. Also, hormone therapy in metastatic breast cancer can increase the risk of colorectal cancer in patients.