Local recurrence after mastectomy and adjuvant CMF: Implications for adjuvant radiation therapy

Background: The purpose of the present study was to evaluate the patterns of failure in a series of patients with node-positive breast cancer that was treated by total mastectomy and adjuvant chemotherapy. Methods: A retrospective review was undertaken of 217 patients with node-positive breast cancer who were referred to the oncology departments of Westmead and Nepean Hospitals following total mastectomy between January 1980 and December 1991. The majority of patients (82%) were pre- or peri-menopausal and all underwent chemotherapy with cyclophosphamide, methotrexate and 5-fluorouracil (CMF) by either an oral or intravenous regimen. No patient received adjuvant radiation therapy. Results: After a median follow up of 8.7 years, 19% of patients had developed a loco-regional recurrence (LRR). The majority of LRR (79%) occurred within the initial 3 years after mastectomy. The risk of LRR was positively associated with the size of the tumour (11% for T₁ vs 53% for T₃, P < 0.001) and axillary nodal status (16% for three or fewer positive nodes vs 31% for four or more positive nodes, P = 0.017). Patients with T₁ or T₂ tumours and 1-3 positive nodes had the lowest rate of LRR (11%) while those with T₃ tumours or 4-10 positive nodes had the highest rates, ranging from 23 to 75%. Relapse at the chest wall and supraclavicular fossa (SCF) accounted for 46 and 35%, respectively, of all LRR; relapse at the internal mammary chain and axilla was uncommon. Conclusion: The data suggest that patients with T₃ tumours (> 5 cm) and any nodal involvement or patients with four or more involved axillary nodes, regardless of T stage, are at a high risk of LRR and will benefit from adjuvant radiation therapy to the chest wall and SCF.