Who should not receive adjuvant chemotherapy? International databases.

Abstract

The optimal selection of patients for adjuvant therapy, avoiding overtreatment and undertreatment, of disease is a significant challenge in the management of early breast cancers. Population-based cohorts in Denmark and in two Swedish health care regions were investigated to identify patients with breast cancer who have a sufficiently low risk of recurrence without adjuvant therapy. Published data on different calcification patterns were also included from the randomized Swedish mammography two-county study. The Danish Breast Cancer Group's population-based registry revealed that patients with lymph node-negative and estrogen receptor- or progesterone receptor-positive cancers of histological grade I that were less than 20 mm in size had a 5-year survival rate similar to age-matched groups without breast cancer. Data from the Stockholm Breast Cancer Group identified a similar risk group (no information on cancer grade) with an approximate 10% risk of dying from breast cancer after 10 years without any adjuvant therapy. In women older than 50 years, approximately 20% died of other causes. Mammographically and lymph node-negative-detected cancers that are less than 15 mm in size generally have an excellent survival outcome, excluding patients with casting calcifications. Patients who have lymph node-negative breast cancers that are less than 20 mm in size, combined with estrogen receptor positivity, can be identified as a low-risk group. The vast majority of these patients are unlikely to benefit from the addition of conventional chemotherapy, but some of them may. The dilemma is that we cannot identify these patients prospectively because of the lack of relevant predictive factors for chemotherapy.