Prognostic factors in breast cancer

Lack of prognostic significance of the monoclonal antibody Ki-S1, a novel marker of proliferative activity, in node-negative breast carcinoma

In a series of 205 node-negative breast cancers (NNBC), we determined staining by the novel antibody Ki-S1, a marker of tumor cell proliferation, in order to test its association with other prognostic variables and its prognostic significance. Ki-S1 was determined in routinely formalin-fixed paraffin-embedded tumor samples. Ki-S1 gave a nuclear staining in the majority of the carcinomas (188 of 205), with percentages of reacting nuclei ranging from 2% to 90% (median value of 7%). In 107 tumors frozen sections were available to also assess the Ki-67 antibody. Among these, 94 had a nuclear staining of cancer cells ranging from 5% to 80% (median value of 7%). In 46 tumors we also determined the MIB-1 antibody. The percentage of MIB-1 nuclear staining ranged from 1% to 50% (median value of 20%). There was no significant relationship between Ki-S1 and the other two cell kinetic markers. Ki-S1 labeling was significantly associated only with tumor size (p = 0.03). With a median follow-up of 6 years, Ki-S1 had no significant prognostic value for either relapse-free survival (RFS) or overall survival (OS) (Ki-S1 as continuous logarithmic variable; p = 0.86 and p = 0.23, respectively). For RFS the following variables had a significant prognostic value: Ki-67 (< or = 10% vs > 10%; p = 0.037); progesterone receptor (PgR) expression (- vs+/++; p = 0.041); tumor size (pT1 vs pT2-3; p = 0.042) and grading (GI vs GII-III; p = 0.047). For OS, tumor size (p = 0.0044), age (continuous variable; p = 0.0060), and Ki-67 (p = 0.043) were significantly prognostic. In multivariate analysis (final model), only tumor size retained a significant and independent prognostic value for RFS (p = 0.0042). For OS, both tumor size (p = 0.0029) and age (< or = 55 years vs > 55 years; p = 0.041) retained significance in the multivariate model. In conclusion, Ki-S1 does not seem to have prognostic relevance in this series of NNBC. Possible hypotheses to explain this observation are discussed.

Effect of a cytotoxic analog of LH-RH (T-98) on the growth of estrogen-dependent MXT mouse mammary cancers: correlations between growth characteristics and EGF receptor content of tumors

Female BDF mice bearing estrogen-dependent MXT mouse mammary cancers were treated for 4 weeks with a cytotoxic analog of luteinizing hormone-releasing hormone (LH-RH). T-98 (agonist [D-Lys6]LH-RH linked to glutaryl-2(hydroxymethyl)anthraquinone). The effects of T-98 were compared to those of equimolar amounts of the cytotoxic moiety 2-(hydroxymethyl)anthraquinone hemiglutarate (G-HMAQ) and carrier LH-RH agonist [D-Lys6]LH-RH. Both T-98 and [D-Lys6]LH-RH significantly inhibited the growth of MXT cancers, but G-HMAQ had only a minor non-significant effect. Cytotoxic analog T-98 and the carrier [D-Lys6]LH-RH had similar inhibitory hormonal activities on the pituitary-gonadal axis, but T-98 caused a larger reduction in tumor volume and decreased proliferation characteristics such as mitotic activity and AgNOR numbers in tumor cells to a greater extent than the carrier. Tumor inhibition by T-98, [D-Lys6]LH-RH, and ovariectomy was connected with a significant decrease in binding capacity of EGF receptors in tumor cell membranes. The concentration of EGF receptors remained high in tumors that continued to enlarge in spite of treatment and in all control untreated tumors, even those of small size. Thus, the changes in EGF receptors are likely to be the result of the therapy. Treatment with T-98 caused a greater reduction in the binding capacity of EGF receptors in tumors than [D-Lys6]LH-RH. This could explain the higher inhibitory effect of the cytotoxic analog on tumor growth. Since radiolabeled T-98 was shown to accumulate in MXT cancers 3 hours after a subcutaneous injection, this indicates that specific targeting might play a role in the antitumor effect exerted by this cytotoxic analog.

Cell kinetics in human breast cancer: comparison between the prognostic value of the cytofluorimetric S-phase fraction and that of the antibodies to Ki-67 and PCNA antigens detected by immunocytochemistry

The determination of cell proliferation is one of the more widely used tools for assessing prognosis. However, additional research in this field is warranted because today there are several methodological procedures available for monitoring cell kinetics and it has still not been established which is the most reliable marker of proliferation and which possesses the greatest prognostic value. We performed this study in a series of primary invasive breast cancers to compare the prognostic value of S-phase fraction (SPF) by flow cytometry, the most widely used method for detecting proliferation at present, with that of antibodies to Ki-67 and PC-10 to proliferating-cell nuclear antigen (PCNA) detected by immunocytochemical methods. A significant linear relationship was observed only between SPF and Ki-67. In univariate analysis SPF and Ki-67 values, nodal status, histological grading and peritumoral lymphatic-vessel invasion were significant predictors of relapse-free survival (RFS). As far as overall survival (OS) is concerned, only SPF, Ki-67 and nodal status were significantly associated with the risk of death. PCNA had no prognostic value for either RFS or OS. In multivariate analysis only SPF and nodal status retained a significant and independent prognostic value. Neither the cell-kinetics parameters assessed by immunocytochemistry (i.e. Ki-67 and PCNA) nor histological grading were independent prognosticators. In conclusion, our results provide evidence that the determination of SPF by flow cytometry was the strongest cell-kinetics marker used to assess prognosis in this series of breast cancers. However, different and novel markers of cell kinetics need to be compared in larger series in order to identify the best one.