Background: pT1N0M0 breast carcinoma (< or = 2 cm in greatest dimension, lymph node negative) is associated with generally favorable 5-year and 10-year survival, but to the authors' knowledge there are few data available regarding the long term outcome of these patients.
Methods: The authors identified women with breast carcinoma diagnosed between 1945-1984 in a geographically defined urban population using the files of the Finnish Cancer Registry and local hospital records (n = 1495). The clinical and autopsy records and histologic slides were reviewed. The series contained 265 patients with unilateral pT1N0M0 breast carcinoma treated with mastectomy and axillary lymph node dissection without adjuvant systemic therapy and who were followed for 10-44 years (median, 17 years) after the initial diagnosis or until death.
Results: The last death from pT1N0M0 breast carcinoma occurred 23 years after the initial diagnosis. The 20-year overall survival rate was 54% (95% confidence interval [95% CI], 48-60%) and the survival rate when corrected for intercurrent deaths was 81% (95% CI, 75-87%). The 20-year survival rate when corrected for intercurrent deaths was 92% (95% CI, 86-98%) in patients with T1a-b disease (primary tumor < or = 10 mm), but was only 75% (95% CI, 64-86%) in patients with pTc disease (range, 11-20 mm). None of the patients with well differentiated (World Health Organization Grade 1) pTa-b tumors died of breast carcinoma (n = 48) whereas the 20-year survival rate when corrected for intercurrent deaths was 81% (95% CI, 67-95%) in patients with Grade 2-3, pT1a-b tumors (P = 0.002).
Conclusions: Patients with well differentiated pT1a-b tumors form a subgroup with excellent long term prognosis, but a significant proportion of women with either moderately or poorly differentiated pT1a-b tumors or pT1c tumors ultimately die of the disease.