New therapeutic possibilities in primary invasive breast cancer

Current therapy for small invasive breast cancer, particularly when discovered mammographically, was re-examined. Axillary dissection may be avoided when lymph node metastases incidence is low (< 10%) or when primary cancer features determine adjuvant therapy. Radiation therapy may be avoided when risk of recurrence is very low.

Recent studies by the Surveillance, Epidemiology, and End Results program (SEER) have shown increases in small invasive breast cancers (< 1 cm) attributable to mammographic screening. The incidence of axillary metastases in mammographically discovered small cancers (< 1 cm) may be less than 10%. Follow-up data from the Breast Cancer Detection Demonstration Project (BCDDP) indicate a disease-free survival rate exceeding 95% at 8 years if the cancer was discovered mammographically.

Maximum diameter and lymph node metastases of invasive breast cancer diagnosed between 1969 and 1988 were analyzed and compared to cases diagnosed between 1929 and 1968. One hundred thirty patients have been treated without either axillary dissection or radiation therapy since 1980.

The mean and median diameters of invasive breast cancers decreased to 2.31 and 2.0 cm, respectively, between 1984 and 1988; 13% were less than 1 cm in diameter. Only 13% of patients had axillary metastases if the primary cancer was 1 cm or less in diameter in the last 10 years; 71% had only 1 or 2 nodes involved. Isolated local recurrence, total local recurrence, and distant metastases were unchanged when radiated and nonirradiated patients were compared. Axillary nodal recurrence was decreased in irradiated patients because the lower half of the axilla was treated.

In selected patients with very small invasive breast cancers detected by mammography, breast conservation without axillary dissection or radiation therapy may be used. Entirely outpatient treatment markedly reduces morbidity and cost, and furthers the gains from screening programs.