Objective: To compare the differences in the clinicopathological and molecular biological features between the breast cancer patients with estrogen receptor (ER)+/progesterone receptor (PR)+ or ER+/PR- tumors.
Methods: The clinicopathological data of 3124 female breast cancer patients with known ER/PR expression status, 2220 being ER+/PR+ and 904 being ER+/PR-, and 1484 being ER-/PR-, were analyzed retrospectively. Immunohistochemistry was used to detect the expression of c-erb and cathepsin D in the tumor specimens.
Results: The average peak onset age was 50 years in both the ER+/PR+ and ER+PR- patients, and the mean age of the ER+/PR+ patients was 52.40 years, not significantly different from that of the ER-/PR- patients (52.57 years, P = 0.709). The peak onset age of the ER+ patients was 50 years, significantly higher that that of the ER- patients (48 years, P = 0.001), and the mean age of the ER+ patients was 52.46 years, significantly higher than that of the ER- patients (51.42 years, P = 0.001). Univariate analysis showed that ER+/PR- tumors tended to be larger. 24.8% of the ER+/PR- patients had 4 or more metastatic lymph nodes, a rate significantly higher than that of the ER+/PR- patients (20.7%, P = 0.004). The tumors of 18% of the ER+/PR- patients were at the grade III, a rate significantly higher than that of the ER+/PR+ patients (13.5%, P = 0.008). The strong positivity rate of the ER+/PR+ tumors was 23.4%, ignorantly higher than hat of the ER+/PR- tumors (11.2%, P = 0.000). The c-erB-2 positive rate of the ER+/PR+ tumors was 19.7%, significantly lower than that of the ER+/PR- tumor group (28.7%, P = 0.000). The cathepsin D positive rate of the ER+/PR- group was 76.9%, significantly higher than that of the ER+/PR- group (71.9%, P = 0.005). Multivariate analysis indicated that positive PR expression was associated with the level of ER (OR = 1.792, 95% CI = 1.484 - 2.164, P = 0.000), cathepsin D (OR = 1.380, 95% CI = 1.023 - 1.862, P = 0.035) and c-erbB-2 (OR = 0.639, 95% CI = 0.463 - 0.883, P = 0.007).
Conclusion: ER+/PR+ and ER+/PR- tumors may have identical etiology. The mechanism of whether PR is expressed in ER+ breast cancer may be caused by different factors, which causing many different aspects. According to these differences, new target of therapy may provide the possibility of improving the response and prognosis for patients with ER+/PR- tumors.