Is there an increased incidence of adenomatous polyps in breast cancer patients?

Patients with breast cancer may be at higher risk of colorectal neoplasia

Background

The risk of colorectal neoplasia in breast cancer survivors is unclear. This study aimed to determine the colonic adenoma detection rate (ADR) in patients with breast cancer.

Methods

We conducted a retrospective study of patients with breast cancer who underwent a colonoscopy between 2000 and 2017. A control group (n=3295), comprising cancer-free patients undergoing their first screening colonoscopy, was used for comparison.

Results

Of 62,820 breast cancer patients, 3304 met the inclusion criteria. The mean age at the time of first colonoscopy was 59 years. ADR was 55%; 1803 patients had adenomas. High-grade dysplasia was evident in 28% of polyps and invasive adenocarcinoma was detected in 172 patients (5%). The median time from breast cancer diagnosis to adenoma detection was 3 years. The ADR was 21% in patients aged <40 years (n=63) and 39% in patients aged 40-50 years (n=314). The ADR was 26% in patients <50 years with a body mass index (BMI) lower than 30 kg/m² or no family history of colorectal cancer. Multivariate logistic regression analysis revealed that the following independent factors were associated with a greater risk of colon adenoma: older age, higher BMI, family history of colorectal cancer, and personal history of breast cancer.

Conclusions

In patients with breast cancer, the ADR was higher than the reported rates for the general population. Screening colonoscopy should be considered soon after breast cancer diagnosis in patients <50 years of age. Further prospective studies investigating our findings are warranted.

Association between breast cancer and the risk of colorectal cancer

BACKGROUND

The literature to date has suggested a potential increase in colorectal cancer (CRC) among patients with breast cancer.

METHODS

We performed a systematic review of the literature and included 37 retrospective cohort studies and 8 case-control studies. The primary aim was to determine the prevalence of CRC. Secondary aims included analysis of adenomatous polyps and analysis of CRC prevalence by age. We calculated pooled prevalence rates and odds ratios (ORs) using random effects models with 95% confidence intervals (CI).

RESULTS

We identified 1,055,917 individuals with breast cancer among whom 9097 cases of CRC were detected. The pooled event rate for CRC was 0.7% (95% CI, 0.6%-0.9%; I²=97%). Four case-control studies reported prevalence of CRC (N=17,873 patients with breast cancer and 70,366 controls), including 46 cases of CRC in the patients with breast cancer, and 272 CRC in the controls (OR, 1.2; 95% CI, 0.4%-3.7%; P = .7). Six studies reported prevalence of advanced adenomas in patients with breast cancer (N=1087) compared with controls (N=1356) with 62 cases of advanced adenomas in patients compared with 47 in the controls (OR, 1.5; 95% CI, 0.97-2.2; P = .07). In patients with breast cancer <50 years old (4 studies, N=64,706), the pooled OR was increased (OR, 2.5; 95% CI, 1.7-3.5; P =.001). In 3 studies of women <45 years old (N=92,594), the risk was increased (OR, 2.3; 95% CI, 1.7-2.6; P < .001).

CONCLUSIONS

Patients with breast cancer should not undergo CRC screening at intervals different from the general population. In patients with breast cancer <50 years old, CRC screening should be considered at age 45 years.

Diet and adenomatous polyp risk

Studies of risk factors for colonic adenomatous polyps have been reported in greater numbers in 1993 than in all previous years combined. This explosion in interest in polyps has not arisen because polyps themselves cause serious illness. They are in the vast majority of cases asymptomatic. However, adenomas have become the surrogate for colon cancer in a number of phase III dietary intervention trials. These trials were undertaken at a time when very little was known of adenoma risk factors. Data accumulated in the past 18 months in general demonstrate a similarity in risk factors for cancer and polyp. Since it has also been recently established that polypectomy diminishes colon cancer risk, the adenomatous polyp has been established as an ethical and convenient surrogate for cancer of the colon. Prevention of colorectal cancer is the goal of all the above studies, and it is hoped that the dietary intervention trials currently under way will generate the data that will make prevention possible.

Rectal epithelial proliferation in women recovered from breast cancer

Women recovered from breast cancer are at increased risk for colorectal neoplasia. The reasons may be genetic, dietary or endogenous hormonal risk factors. Measurements of rectal epithelial proliferation are a useful biomarker of risk for large bowel cancer. This was studied in 12 women after (mean 7.8 years) cured breast cancer, who had a mean % labelling index of 7.5 +/- 3.5 (S.D.) as compared to 5.8 +/- 1.8 (S.D.) in a disease-free comparison group of 25 women. In addition, analysis of labelled crypt compartments demonstrated a significantly higher proportion in the study group with thymidine uptake, mainly in the mid crypt zone, and an extension of crypt cell DNA synthesis towards the surface epithelium. Using proliferative activity as a biomarker of risk in a larger study group, we may learn more about common etiological factors for both malignancies and also identify a higher-risk subgroup for long-term follow-up and possible therapeutic intervention.