Can we select which patients with small breast cancers should receive adjuvant chemotherapy?

To identify the risk of systemic metastases from T1a and T1b N0 breast cancers in patients treated in an academic center, and to seek factors to identify the patients at greatest risk of such failure.

With the demonstration that adjuvant chemotherapy reduces the death rate from breast cancer by roughly one quarter across all risk groups, controversy has reigned regarding possible exclusions from therapy. T1a and T1b N0 tumors (1-cm diameter and smaller with negative axillary nodes) have been considered at low risk for metastasis since the report from Memorial Sloan-Kettering Cancer Center of a 90% survival rate at 10 years. Subsequent reports have suggested an even more favorable prognosis for this group. However, consensus statements advise selecting some of these women for treatment, and many do receive adjuvant chemotherapy.

Sequential patients with breast cancer at the Emory Clinic were prospectively staged and followed up for outcome. The records of patients with T1a and T1b N0 tumors were reviewed for exact tumor diameter, grade, receptor status, adjuvant therapy, and outcome. A corrected data set was stripped of patient identifiers and analyzed by Kaplan-Meier methods. Subgroups were formed based on tumor grade (1 vs. 3), adjuvant chemotherapy (use vs. no use), and adjuvant tamoxifen (use vs. no use) and were compared via log-rank tests.

Two hundred eighty-two women were identified. Two developed metastatic disease and one experienced a local failure after breast-conserving treatment. The estimated disease-free survival rate at 10 years was 98.7%. With only two distant failures and one local failure, there was no significant difference by grade, receptor status, or use of adjuvant chemotherapy or tamoxifen.

The risk of systemic failure from such tumors barely exceeded 1% at 10 years. Unless future studies can identify a subgroup at higher risk, the cognitive changes associated with cytotoxic chemotherapy or the loss of estrogen involved do not appear to have sufficient offsetting benefit to warrant chemotherapy for this group of women.