The prognostic significance of peripheral lymphocyte counts in patients with breast carcinoma

A retrospective study evaluating five‐year survival rates in relation to pretreatment lymphocyte counts was undertaken in 453 patients with breast carcinoma. Patients with early tumor stages had higher pretreatment lymphocyte counts than those with advanced tumors: five‐year survival in patients with pretreatment counts above 2000 per mm3 was 87% in Stage I, 67% in Stage II, and 57% in Stage III, while the comparable figures in patients with lower counts were 82%, 51%, and 29%. The differences in five‐year survival rates for Stage II and III were significant: z = 1.6955, p = 0.046 and z = 1.8841, p = 0.03. Similar differences were noted in the disease‐free, five‐year survival rates. The corresponding figures in the three tumor stages for patients with counts above 2000/mm3 were 80%, 63%, and 53%, while those for patients with lower counts were 74%, 44%, and 18%. The differences in Stage II and III were also statistically significant: z = 1.8430, p = 0.33 and z = 2.592, p = 0.005 respectively. The possibility that the presence of suppressant factors related to the thymus may influence levels of lymphocytes was evaluated. Comparison of pre‐thymectomy and postthymectomy lymphocyte counts in a control group of patients who had thymectomy for myasthenia gravis revealed a gradual increase of lymphocytes following thymectomy. The increase was significant at the second year following thymectomy. These observations indicate that lymphocyte counts may serve as prognostic indicators in patients with breast cancer. Low lymphocyte counts may be related to the presence of suppressor substances.