Oncogene amplification correlates with dense lymphocyte infiltration in human breast cancers: A role for hematopoietic growth factor release by tumor cells?

One hundred six primary breast cancer samples were analysed for c‐erbB2, int‐2, and c‐myc gene amplification. Surgically confirmed nodal involvement was observed in 42%. Level of gene amplification was studied by Southern and/or slot blottechniques. Amplified c‐erbB2 gene sequences were present in 21.5% of all samples. Int‐2 was amplified in 13.1% and c‐myc was amplified in 10.3%. In a non‐parametric test (Kruskal‐Wallis) a strong negative association was found between high levels of c‐erbB2 amplification and absence of estrogen receptor (ER) (P = .0009) or progesterone receptor (PR) (P = .011) expression. No correlations were found between all or high levels of amplification of each oncogene separately or combined with T, N, grade, multifocality of tumor, or associated carcinoma in situ. There was a trend approaching statistical significance for patients with c‐erbB2 amplifications to have positive lymph nodes at surgery (P = 0.09). A somewhat surprising finding however was a very strong association between oncogene amplification and dense lymphocyte infiltration of the tumor (P = .05). This correlation is even stronger when only high levels of amplification are considered, either for each oncogene separately (P = .0048) or in combination (P = .007). We propose that malignant cell cytokine production may help explain this observation.