Prognostic value of DNA flow cytometry in the locally recurrent, conservatively treated breast cancer patient

Purpose: This study attempted to determine the prognostic value of DNA flow cytometry in the treatment of patients with locally recurrent, conservatively treated breast cancer. Methods and Materials: Of 433 patients with clinical stage I and II breast cancer treated with conservative surgery and radiotherapy at Yale-New Haven Hospital before January 1985, 50 patients experienced an ipsilateral breast relapse as a first site of treatment failure. Using standard flow-cytometric techniques, DNA ploidy, DNA index, and S-phase fraction (SPF) were measured for 38 of the 50 (76%) paraffin-embedded specimens available for analysis. Results: At a median postrecurrence follow-up of 5.8 years, the 5-year and disease-free survival rates following ipsilateral breast treatment failure were 48% and 54%, respectively. Sixty-three percent of the recurrent tumors were DNA diploid and 37% were aneuploid. Both DNA ploidy and SPF were statistically significant prognostic indicators for 5-year survival and disease-free survival after local recurrence. The 5-year survival rate of the DNA diploid population was 64%, compared with 15% in the aneuploid population (P < .02). Patients with low SPF (< 12%) experienced an 83% 5-year survival rate, com pared with a 24% 5-year survival rate in patients with high SPF (≥ 12%) (P < .03). Ploidy and SPF were combined to define the categories of favorable (diploid, low SPF) and unfavorable (diploid, high SPF or any aneuploid subgroups). Patients in the favorable category experienced an 89% 5-year postrecurrence survival rate and a 100% disease-free survival rate, whereas patients in the unfavorable category had a 24% 5-year survival rate and a 32% disease-free survival rate (P < .01). The flow cytometry as a factor correlated with other clinical parameters previously shown to be of progostic significance in this patient population. In a multivariate analysis, flow cytometry was a statistically significant and independent prognostic factor for disease-free survival following local recurrence. Conclusions: DNA ploidy and SPF as measured by currently available flow-cytometric techniques show promise as a tool in determining prognosis for the patient with locally recurrent breast cancer. Implications of these findings with respect to issues of adjuvant systemic therapy at the time of local recurrence are discussed.