Method of detection of new contralateral primary breast cancer in younger versus older women.

Background: Surveillance for contralateral primary breast cancer after a diagnosis of unilateral breast cancer typically consists of yearly mammography and physical examinations at 3-6 month intervals. Mammography is known to be less sensitive in younger, dense breasts. It is unknown at this time how well mammography performs in young patients to detect a new contralateral primary breast cancer.

Patients And Methods: Patients with contralateral breast cancer diagnosed between 1980 and 2004 were identified from the British Columbia Cancer Agency's Breast Cancer Outcomes Unit database in Vancouver. Characteristics of the tumor at baseline and the contralateral tumor were recorded as well as the method of detection of the contralateral breast cancer. A subset of patients was identified based on the age at which they were diagnosed with their initial primary cancer: < 40 years (group A) and 55-59 years (group B). chi2 and independent-sample t tests were used for between-group comparisons.

Results: Older patients were significantly more likely to have their second primary tumor detected by routine follow-up mammography compared with the younger cohort (P < 0.001). Older patients were also more likely to have estrogen receptor-positive, lower grade second primary tumors, and there was a trend toward smaller tumors. Tumors detected by mammography were more likely to be lower grade, estrogen receptor positive, and smaller.

Conclusion: Older patients were more likely to have a contralateral breast cancer detected by conventional mammography, whereas younger patients tended to have cancer detected by physical examinations or by self-diagnosis. Better imaging techniques are required to detect new contralateral primary breast cancer in younger patients.