Breast cancer survivors may be at increased risk for developing colorectal polyps and colorectal cancer because of shared genetic, hormonal, and lifestyle-related risk factors. However, the prevalence of colorectal neoplasia in women with breast cancer has not been clearly established.

This prospective screening study aims to evaluate the prevalence of colorectal polyps, adenomas, and colorectal cancer detected by screening colonoscopy in women who have completed treatment for breast cancer. The study also investigates whether clinical, pathological, and genetic characteristics of breast cancer are associated with the risk of colorectal neoplasia.

All eligible participants undergo screening colonoscopy after completion of breast cancer treatment. The findings of this study may help identify breast cancer survivors who could benefit from individualized colorectal cancer screening strategies and contribute to improving long-term cancer survivorship care.

Breast cancer is the most commonly diagnosed malignancy among women worldwide. Improvements in early detection and treatment have substantially increased survival rates, leading to a growing population of breast cancer survivors. Consequently, the identification of secondary malignancies and long-term cancer-related health risks has become increasingly important.

Several epidemiological studies have suggested a possible association between breast cancer and colorectal neoplasia. Shared risk factors, including age, obesity, hormonal exposure, genetic susceptibility, and environmental influences, may contribute to the development of both malignancies. However, available evidence remains inconsistent, and prospective studies evaluating the prevalence of colorectal neoplasia in breast cancer survivors are limited.

This prospective single-center screening study was conducted to determine the prevalence of colorectal neoplasia detected by screening colonoscopy in women previously diagnosed with breast cancer. Female patients older than 18 years who had completed surgical, systemic, and/or adjuvant treatment for breast cancer were prospectively enrolled. All participants were asymptomatic with respect to gastrointestinal complaints and underwent screening colonoscopy after completion of breast cancer treatment. Patients undergoing colonoscopy for diagnostic indications or presenting with alarm gastrointestinal symptoms were excluded.

Clinical and demographic data, including age, body mass index, comorbidities, family history, breast cancer pathology, molecular subtype, Ki-67 proliferation index, treatment history, and available genetic testing results, were collected. Colonoscopic findings were recorded, and all detected lesions underwent histopathological evaluation. Adenomas were classified according to established histological criteria.

The primary objective of the study was to determine the prevalence of colorectal neoplasia, defined as adenomatous polyps and colorectal carcinoma, among breast cancer survivors undergoing screening colonoscopy. Secondary objectives included evaluation of adenoma detection rate (ADR), colorectal cancer prevalence, and identification of clinical, pathological, and genetic factors associated with colorectal neoplasia and colorectal cancer development.

The results of this study may contribute to the development of risk-adapted colorectal cancer screening strategies in breast cancer survivors and improve understanding of factors associated with colorectal neoplasia in this population.

Inclusion Criteria:

• Women aged ≥18 years
• Diagnosis of breast cancer
• Completed surgical and/or systemic treatment
• Underwent or planned to undergo screening colonoscopy after completion of breast cancer treatment
• Asymptomatic at the time of colonoscopy

Exclusion Criteria:

• Age <18 years
• History of colorectal malignancy
• History of inflammatory bowel disease
• Inadequate bowel preparation (Boston Bowel Preparation Scale not adequate)
• Incomplete medical records
• Refusal to participate
• Colonoscopy performed for diagnostic purposes rather than screening
• Presence of gastrointestinal alarm symptoms (e.g., rectal bleeding, iron deficiency anemia, change in bowel habits, weight loss, abdominal pain, positive FIT/FOBT, or suspicious radiologic findings)

Individual participant data underlying the results reported in this study, after de-identification, will be available upon reasonable request to the corresponding author. The study protocol will also be made available.

Data will be available beginning 6 months after publication and ending 5 years after publication for researchers who provide a methodologically sound proposal, subject to institutional approval and applicable regulations regarding patient confidentiality.

Data will be available beginning 6 months after publication and ending 5 years after publication for researchers who provide a methodologically sound proposal, subject to institutional approval and applicable regulations regarding patient confidentiality.