The association between telomerase, histopathological parameters, and KI-67 expression in breast cancer

BACKGROUND

Telomerase is a ribonucleoprotein enzyme that appears to play an important role in carcinogenesis. Telomerase reactivation seems to be associated with immortalization and malignancy.

METHODS

Using a polymerase chain reaction (PCR)-based assay known as the TRAP (telomeric repeat and amplification protocol) assay, we examined telomerase activity in 60 breast specimens prospectively collected from 39 patients undergoing elective breast surgery in our center. The specimens included adjacent noncancerous breast (n = 21), benign breast disease (n = 5), and infiltrating carcinoma (n = 34). Ki-67 expression was determined in 32 invasive breast cancer specimens using immunohistochemistry techniques. The histopathological features were determined by light microscopy by an experienced breast pathologist.

RESULTS

Telomerase activity was detected in 24 (71%) of 34 infiltrating carcinomas. None of the adjacent noncancerous specimens nor the benign breast lesions expressed telomerase activity. Telomerase reactivation was significantly associated with nodal metastasis and Ki-67 expression. There was no significant association between telomerase activity and menopausal status, tumor grade, or tumor size.

CONCLUSIONS

Telomerase reactivation is associated with the acquisition of malignancy in the human breast. Telomerase activity is significantly associated with nodal metastasis and cellular proliferation as measured by Ki-67 expression in human breast cancer.

Telomerase activity and prognosis in breast cancer

AIMS

Telomerase is a ribonucleoprotein enzyme which appears to play an important role in carcinogenesis. Its reactivation is associated with the acquisition of immortalization and malignancy. The present study aims to examine the association between telomerase activity and prognosis in breast cancer.

METHODS

Using a PCR-based assay, we retrospectively examined telomerase activity in 45 frozen human breast cancer specimens. Telomerase activity was compared with histopathological and clinical data.

RESULTS

Telomerase activity was detected in 20 (44%) of 45 cases and was associated with advanced histopathological grade and tumour type (ductal vs. lobular). The association with these histological parameters was statistically significant (chi-squared test P<0.05). There was no significant difference in the overall survival rate (78 vs. 77%) or disease-free survival (73 vs. 69%) at 5 years (Kaplan-Meier method, log-rank test P>0.05).

CONCLUSIONS

The present results indicate that telomerase activity in human breast cancer is not associated with nodal status or disease outcome.

Control of aromatase activity in breast tumours: the role of the immune system

Cytokines such as interleukin-6 (IL-6) and tumour necrosis factor alpha (TNF alpha), have been identified as important regulators of aromatase activity in fibroblasts derived from normal and malignant breast tissues, and may play an important role in controlling aromatase activity in breast tumours. The major source of such cytokines within breast tumours remains to be established but macrophages and lymphocytes, which can infiltrate tumours, have been identified as a potential source of aromatase stimulatory cytokines. To obtain further insight into the possible role played by the immune system in cancer development, and in particular its ability to regulate aromatase activity via cytokine production, we have obtained peripheral blood monocytes and lymphocytes from an immunosuppressed kidney transplant recipient, receiving cyclosporin A therapy, and a woman with breast cancer. Monocytes and lymphocytes were stimulated with lipopolysaccharide (LPS), and the conditioned medium (CM) collected from these cells was tested for its ability to stimulate aromatase activity in fibroblasts derived from normal breast tissue from a woman undergoing lumpectomy for the removal of a breast tumour. The white blood cell count was lower for the immunosuppressed patient, mainly because of the reduction in the number of monocytes and lymphocytes. The ability of CM from the monocytes and lymphocytes of the immunosuppressed patient to stimulate aromatase activity was significantly reduced (68% and 82% for monocytes and lymphocytes, respectively) compared with that of CM from the cells of the woman with breast cancer. It is possible, therefore, that immunosuppression, which has been found to be associated with a reduction in the incidence of de novo breast cancer in kidney transplant recipients, may exert its effect by inhibiting cytokine production by the cells of the immune system and thus oestrogen synthesis. In contrast to the stimulatory effects that TNF alpha has on aromatase activity in breast fibroblasts, in MCF-7 breast cancer cells, which possess low aromatase activity, it reduced activity. However, the extent of inhibition of aromatase activity in these epithelial cells was much lower than the marked stimulation which it can induce in breast fibroblasts.

Re-excision operations in nonpalpable breast cancer

We retrospectively reviewed the records of 317 needle-localization (NL) biopsies performed at the Royal Marsden Hospital during 1989-1992. The malignancy yield in our centre, where there is an emphasis on cooperation with an experienced radiologist and breast pathologist, was 48% (151/317), with benign to malignant biopsy ratio of 1:1:1. Analysis of the histopathological findings of the malignant lesions revealed a 45% (68/51) incidence of positive microscopic margins. Of these 68 patients, 50 had re-excisions, including nine patients who required mastectomy. Twenty-eight of the re-excisions (56%) contained residual tumour, of which five (18%) were invasive carcinoma > 3 mm (size range 1-19 mm) and 13 (46%) were residual DCIS > 1 mm (size range 1-40 mm). Our findings suggest a significant incidence of residual disease associated with positive microscopic margins in NL-detected nonpalpable cancers. Therefore, our current practice of performing a wider re-excision for positive margins is justified. Stereotactic fine-needle aspiration cytology was not performed by the radiologist referring these cases, but it should be performed preoperatively and if the test is positive, definitive treatment in the form of wide local excision or quadrantectomy is carried out in the first instance in order to avoid a second-surgical procedure.