Finasteride treatment and male breast cancer: a register-based cohort study in four Nordic countries

Hair loss during and after breast cancer therapy

For patients diagnosed with breast cancer, alopecia can be a distressing side effect of treatment. Major surgeries, cytotoxic chemotherapy, and endocrine therapy may result in several different types of alopecia. This article reviews the underlying mechanisms, etiology, prevention strategies, and treatment options for chemotherapy-induced alopecia, telogen effluvium, and endocrine-induced alopecia. Here, we aim to provide breast oncologists with a review of the types of hair loss related to cancer therapy and current preventative and treatment options to facilitate informative patient counseling.

Computationally repurposing drugs for breast cancer subtypes using a network-based approach

‘De novo’ drug discovery is costly, slow, and with high risk. Repurposing known drugs for treatment of other diseases offers a fast, low-cost/risk and highly-efficient method toward development of efficacious treatments. The emergence of large-scale heterogeneous biomolecular networks, molecular, chemical and bioactivity data, and genomic and phenotypic data of pharmacological compounds is enabling the development of new area of drug repurposing called ‘in silico’ drug repurposing, i.e., computational drug repurposing (CDR). The aim of CDR is to discover new indications for an existing drug (drug-centric) or to identify effective drugs for a disease (disease-centric). Both drug-centric and disease-centric approaches have the common challenge of either assessing the similarity or connections between drugs and diseases. However, traditional CDR is fraught with many challenges due to the underlying complex pharmacology and biology of diseases, genes, and drugs, as well as the complexity of their associations. As such, capturing highly non-linear associations among drugs, genes, diseases by most existing CDR methods has been challenging. We propose a network-based integration approach that can best capture knowledge (and complex relationships) contained within and between drugs, genes and disease data. A network-based machine learning approach is applied thereafter by using the extracted knowledge and relationships in order to identify single and pair of approved or experimental drugs with potential therapeutic effects on different breast cancer subtypes. Indeed, further clinical analysis is needed to confirm the therapeutic effects of identified drugs on each breast cancer subtype.

Pharmacological Management of Pattern Hair Loss

Pattern hair loss (PHL) is a condition that worsens with time and the only way it can be slowed down is with pharmacological intervention. Pharmacological treatments for PHL, from an evidenced-based perspective with respect to safety and efficacy, are limited to only two drugs, minoxidil and finasteride. However, there are a host of drugs being used, off-label with limited evidence. This article attempts to review the literature on this topic, and the authors add to this, with their experience of over two decades on incorporating pharmacologic treatments along with hair transplantation in their management of PHL.

Characteristics of finasteride users in comparison with nonusers: A Nordic nationwide study based on individual-level data from Denmark, Finland, and Sweden

PURPOSE

Published epidemiological studies on the association between finasteride use and the risk of male breast cancer have been inconclusive due to methodological limitations including a few male breast cancer cases included. Determinants of male breast cancer have been studied, but it remains unexplored whether these are also related to finasteride use and thereby constitute potential confounders. This study aimed to assess whether there are differences between finasteride users and nonusers with regard to numerous potential confounders.

METHODS

In total, 246 508 finasteride users (≥35 years) were identified in the prescription registries of Denmark (1995-2014), Finland (1997-2013), and Sweden (2005-2014). An equal number of nonusers were sampled. The directed acyclic graph (DAG) methodology was used to identify potential confounders for the association between finasteride and male breast cancer. A logistic regression model compared finasteride users and nonusers with regard to potential confounders that were measurable in registries and population surveys.

RESULTS

Finasteride users had higher odds of testicular abnormalities (odds ratio [OR] 1.40; 95% confidence interval [CI] 1.36-1.44), obesity (1.31; 1.23-1.39), exogenous testosterone (1.61; 1.48-1.74), radiation exposure (1.22; 1.18-1.27), and diabetes (1.07; 1.04-1.10) and lower odds of occupational exposure in perfume industry or in high temperature environments (0.93; 0.87-0.99), living alone (0.89; 0.88-0.91), living in urban/suburban areas (0.97; 0.95-0.99), and physical inactivity (0.70; 0.50-0.99) compared to nonusers.

CONCLUSIONS

Systematic differences between finasteride users and nonusers were found emphasizing the importance of confounder adjustment of associations between finasteride and male breast cancer.

Metachronous Contralateral Male Breast Cancer: Case Report and Literature Review

Male breast cancer (MBC) is rare and consequently understudied. Here we present the case of contralateral breast cancer in a male patient nearly a quarter century following his initial breast cancer diagnosis and treatment. The epidemiology, risk factors, diagnosis, characterization, treatment, and prognosis of male breast cancer are reviewed. MBC accounts for <1% of all breast cancer with an estimated incidence nearly 1.25 per 100,000 person years. Our patient tested positive for ATM mutation of undetermined significance. More commonly in males, a BRCA2 mutation confers a >1 in 15 lifetime risk of breast cancer and is present in >11% of MBC patients, while BRCA1 is present in an estimated <1.5% of MBC patients. The risk of contralateral breast cancer developing in a male with a unilateral lesion is much higher than for a primary male breast cancer in the general population. Men tend to be diagnosed at a later age and stage than females. Prognosis for male and female breast cancer is similar considering both age of patient and stage of the tumor at diagnosis, and similar treatment paradigms have resulted in similar outcomes. Although lumpectomy with radiation therapy may have the same prognosis as mastectomy, the standard of care for male breast cancer continues to be simple mastectomy with sentinel lymph node biopsy.

Analysis of Data From Breast Diseases Treated With 5-Alpha Reductase Inhibitors for Benign Prostatic Hyperplasia

OBJECTIVE

5-alpha reductase inhibitors (5ARIs) decrease the androgen levels in vivo and are currently used for the treatment of benign prostatic hyperplasia (BPH) in men. However, these inhibitors can also increase the risk of gynecomastia, breast tenderness, and breast cancer. Hence, we did a systematic review and meta-analysis to evaluate the rate of breast-related diseases in men treated with 5ARIs.

MATERIALS AND METHODS

PubMed, Embase, Cochrane, and CNKI databases were searched for randomized controlled trials using 5ARIs in patients with BPH. Data were analyzed by using Cochrane Collaboration review manager program and Stata 12.0 software.

RESULTS

In total, 14 studies were included in the meta-analysis. Gynecomastia was significantly more common with 5ARIs treatment when compared with placebo (3.30% vs. 1.84%; P < .00001) or alpha blockers (ABs) monotherapy (2.33% vs. 1.00%; P = .0009). Both dutasteride (2.03% vs. 0.90%; P < .00001) and finasteride (4.08% vs. 2.43%; P < .00001) are associated with significantly higher risk of gynecomastia than placebo. Risk for breast tenderness was elevated in 5ARIs users (0.83% vs. 0.25%; P = .01) or in users having combination therapy with ABs (2.48% vs. 0.58%; P < .0001). Finasteride is associated with significantly higher risk of breast tenderness than placebo (0.80% vs. 0.25%; P = .02).

CONCLUSION

In male patients with BPH, 5ARIs have significantly increased the risk of gynecomastia and breast tenderness but may be not to the breast cancer. In addition, combination therapy is significantly associated with higher risk of breast tenderness compared to single ABs monotherapy.

Finasteride Use and Risk of Male Breast Cancer: A Case-Control Study Using Individual-Level Registry Data from Denmark, Finland, and Sweden

BACKGROUND

In case reports, concerns have been raised as to whether finasteride use increases the risk of male breast cancer. Previous epidemiologic evidence on the potential link is conflicting. This study aimed to assess whether an association between finasteride use and male breast cancer exists after accounting for potential confounders.

METHODS

The source population consisted of all men (≥35 years) from Denmark (1995-2014), Finland (1997-2013), and Sweden (2005-2014). Cases with incident male breast cancer were identified in the cancer registries and matched with 50 density-sampled, age, and country-matched male population controls per case. Exposure information on finasteride use was derived from the prescription registries. Potential confounders were identified using the directed acyclic graph methodology and measured by use of information from nation-wide registries.

RESULTS

The study population comprised 1,005 male breast cancer cases and 43,058 controls. Confounder-adjusted odds of finasteride exposure were not statistically significantly increased [OR, 1.09; 95% confidence interval (CI), 0.77-1.54] in breast cancer cases relative to controls. There was no evidence of a dose-response relationship, as the group with greatest exposure to finasteride was associated with lowest OR of male breast cancer [OR, 0.72 (95% CI, 0.40-1.30)]. Sensitivity analyses did not reveal marked changes in results with different exposure definitions or for specific subgroups.

CONCLUSIONS

Results from this study provided no evidence that finasteride use was associated with male breast cancer.

IMPACT

This large confounder-adjusted study supports the view that exposure to finasteride is not associated materially with male breast cancer risk.

Safety of 5α-reductase inhibitors and spironolactone in breast cancer patients receiving endocrine therapies

PURPOSE

To provide dermatologists and oncologists with a foundation for practical understanding and uses of 5α-reductase inhibitors and spironolactone for breast cancer patients and survivors receiving endocrine therapies (ETs), including the effect of these treatments on sex hormone levels, any reported drug interactions, and any risk of malignancy.

METHODS

All published studies from January 1978 through April 2018 were considered, using databases such as PubMed, Google Scholar, and Science Direct. Forty-seven studies were included in this review.

RESULTS

There is no evidence of interactions between 5α-reductase inhibitors and spironolactone with ETs used in breast cancer. Sex hormone alteration with 5α-reductase inhibitor or spironolactone use is variable. Three randomized controlled trials, 1 case-control study, and 6 retrospective cohort studies, including 284 female patients, studied the effects of 5α-reductase inhibitors on serum estrogen levels. Levels were increased in 97 of 284 (34%) patients, decreased in 15 of 284 (5.3%) patients, and unchanged in 162 of 284 (57%) patients. Four retrospective cohort studies, 1 case study, and 1 double-blinded crossover study, including 95 female patients, assessed the effect of spironolactone on estrogen levels. Levels were increased in 25 of 95 (26%) patients, decreased in 6 of 95 (6.3%) patients, and unchanged in 64 of 95 (67%) patients. Ultimately, most patients did not have a significant alteration in the level of estrogen when using 5α-reductase inhibitors or spironolactone. No consistent evidence of increased risk of female breast cancer while on spironolactone was reported in 3 studies including 49,298 patients; the risk of breast cancer with the use of 5α-reductase inhibitors has not been studied.

CONCLUSIONS

Most patients did not show increased estrogen levels with spironolactone and there were no data suggesting increased risk of breast cancer. Based on hormonal and pharmacological activity, spironolactone may be considered for further research on alopecia and hirsutism in breast cancer patients.

Finasteride treatment and male breast cancer: a register-based cohort study in four Nordic countries

A potential link has been suggested between dispensed finasteride and increased risk of male breast cancer (MBC). Due to the rare occurrence of MBC, it remains to be established if such a relationship exists. The purpose of this study was to combine nationwide registers in four countries to assess the potential association between dispensed finasteride and MBC. A cohort of all males with dispensed finasteride in Denmark, Finland, Norway, and Sweden (1,365,088 person years) was followed up for up to 15 years for breast cancer, and compared to a cohort of males unexposed to finasteride. Individual‐level register data included country, dates of dispensed finasteride, MBC diagnosis, and death. Incidence rate ratios (IRRs) were estimated using a generalized linear model with a Poisson distribution. An increased risk of MBC was found among finasteride users (IRR = 1.44, 95% confidence interval [95% CI] = 1.11–1.88) compared to nonusers. The IRR increased to 1.60 (95% CI = 1.20–2.13) when users in Norway and Sweden with short follow‐up time were excluded. The highest IRR was seen among men with medium duration of dispensed finasteride, medium accumulated consumption of finasteride, and among men with first dispensed finasteride prescription 1–3 years prior to diagnosis. The analyses suggested possible ascertainment bias and did not support a clear relationship between dispensed finasteride and MBC. In conclusion, a significant association between dispensed finasteride and MBC was identified. However, due to limited data for adjustment of potential confounding and surveillance bias in the present study, further research is needed to confirm these results.