HER2 Low Expression in Primary Male Breast Cancer.

Purpose: The introduction of HER2-targeting antibody drug conjugates (ADCs) offers new treatment options for female breast cancer patients (FBC) expressing low levels of HER2 (HER2 low). No evidence was found that HER2 low describes a new FBC subtype. There is a lack of studies determining the impact of HER2 low in male breast cancer (MBC). In this study, we evaluate the prevalence of HER2 low in primary MBC and correlate the results with patient characteristics. Patients and Methods: In this study, histological specimens were obtained from 120 male patients diagnosed and treated for primary invasive breast cancer from 1995 to 2022 at Breast Cancer Units in Bergisch Gladbach, Chemnitz, and Zwickau, Germany. HER2 immunostaining and in situ hybridization were performed by central pathology and evaluated based on the ASCO/CAP guidelines. The correlation of expression of HER2 low with tumor biological characteristics and patient outcomes was investigated. Results: Out of all cases, four patients (3.3%) showed HER2 positivity (3+), 39 (32.5%) patients were classified as HER2 low, 7 (5.8%) were HER2 2+ (no amplification), 32 (26.7%) were HER2 1+, and 77 (64.2%) were classified as HER2 zero. Out of 77 HER2 zero cases, 47 tumors (61.0%) showed incomplete staining, with <10% of tumor cells classified as HER2 ultralow. No statistical correlation between HER2 low and tumor biological characteristics and patients' survival was found. Conclusion: Our findings show a notable, albeit lower, prevalence of HER2 low expression in primary MBC. However, tumors expressing HER2 low do not show specific tumor biological features to define a new breast cancer subtype in MBC. Our results suggest that a significant number of MBC patients could benefit from ADCs, as shown in FBC. Further studies are required to better understand HER2 low breast cancer, both generally and in MBC.

Prognostic relevance of Ki67 expression in primary male breast cancer: determination of cut-off points by different evaluation methods and statistical examinations.

PURPOSE: 1% of all breast cancer cases occur in men. There are significant differences regarding clinical behaviour and genetic profiles between female (FBC) and male breast cancer (MBC). Parameters for decision-making on treatment and prognosis are derived from FBC. Ki67 has a high value as a prognostic and predictive factor in FBC, but accurate Ki67 cut-off points for MBC are missing. In this study, we aimed to evaluate adequate examination methods and reliable cut-off points for Ki67 to assess the highest prognostic value for patient's overall survival (OS). METHODS: In this multicentric retrospective study, histological specimens were obtained from 104 male patients who were diagnosed and treated for primary invasive breast cancer. We applied three methods of Ki67 analysis: Tumor average scoring (TA), tumor border scoring (TB) and hot-spot scoring (HS). Calculated Ki67 cut-off points for each method were assessed as a threshold for patients' overall survival (OS). RESULTS: Ki67 cut-off points were 13.5 for the TA group, 22.5 for the HS group and 17.5 for the TB group. Only Ki67 TA cut-off calculations demonstrated statistical significance (p = 0.04). Ki67 expression analysis of TA showed that more than 90% of patients with low Ki67 levels (< 13.5) were alive after 5-year follow-up. CONCLUSION: Our findings demonstrate that determination of Ki67 expression in TA is the most reliable to define a cut-off point with high prognostic value. A Ki67 cut-off point of 13.5 shows highest statistical power to define luminal A subgroup and OS.

Quantitative perineural invasion is a prognostic marker in prostate cancer.

This study aimed to investigate the prognostic value of a quantitative, detailed, yet practical analysis of perineural invasion in radical prostatectomy specimens in a high-risk prostate cancer cohort. A total of 114 patients with prostate cancer who underwent radical prostatectomy between 2000 and 2013 were analysed. Using S100 protein immunohistochemistry assisted in the detection of nerves. In the area of closest proximity of the tumour to the dorso-lateral margins, nerves were counted and the infiltration of nerves was categorised (0-3). Category 0 was nerves without immediate tumour-cell-contact. All nerves being fully surrounded by tumour (classical perineural carcinosis) were categorised group 3. Two further categories discriminated between nerves that were touched either by carcinoma cells below 50% of the circumference (category 1) or above (category 2). Perineural carcinosis (Pn1) was seen in 61.4% of cases and correlated positively with ISUP grades, pT categories and presence of intraductal carcinoma but failed significance on Kaplan-Meier analysis. A more quantitative analysis of percentual perineural involvement did demonstrate significant survival differences: cases with less than one Pn1-positive nerve in 5 high power fields had longer survival times. Incomplete perineural involvement (category 1-2) did not have a prognostic value, endorsing the current definition of perineural carcinosis as full circumferential encasement of a nerve by tumour cells. A quantitative analysis of the percentage of nerves positive for perineural invasion has a higher prognostic value than the classical dichotomous statement on the mere presence of perineural invasion.