10.1245/ASO.2004.01.001
Annals of Surgical Oncology 11:751-755 (2004)
© 2004 Society of Surgical Oncology
Male Breast Cancer: Is the Incidence Increasing?
Nicole C. F. Hodgson, MD, MSc, FRCSC,
Jaclyn H. Button, MS,
Dido Franceschi, MD,
Frederick L. Moffat, MD and
Alan S. Livingstone, MD
From the Department of Surgery, University of Miami (NCFH, DF, FLM, ASL), and Florida Cancer Data System (JHB), Miami, Florida.
Correspondence: Address correspondence and reprint requests to: Nicole Hodgson, MD, MSc, FRCSC, Room 3550 SCC, Division of Surgical Oncology, 1475 NW 12th Avenue, Miami, FL 33136; Fax: 305-243-4907; E-mail: nhodgson{at}med.miami.edu
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ABSTRACT
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Background: Male breast cancer is rare, and little is known about state population–level patterns of incidence. The primary objective of this study was to determine the incidence of MBC in Florida in comparison with the Surveillance, Epidemiology, and End Results (SEER) program data.
Methods: Study data were obtained from the Florida Cancer Data System (FCDS). All males with pathologically confirmed invasive breast carcinoma diagnosed from 1985 to 2000 were included. Age-adjusted incidence rates, regional incidence rates, and descriptive statistics were calculated. Annual percent change (APC) for the study period was calculated with a linear model. Results were compared with the SEER data.
Results: A total of 1396 cases of MBC were identified. Age-adjusted incidence rates increased from 0.9 cases per 100,000 in 1990 to 1.5 cases per 100,000 in 2000. In 2000, the highest rates were in the age groups of 70 to 75 years (7.9) and 
85 years (12.5). Infiltrating ductal was the most common subtype (92%); less common subtypes included mucinous (2%) and papillary (2%). Localized disease accounted for 45% of all cases, with regional disease in 33%, distant metastases in 7%, and unstaged in 15%. Most incident cases were diagnosed in the Palm Beach–Broward region (23%). The number of cases increased from 56 in 1985 to 132 new cases in 2000. The APC for this 16-year period was 2.0% (95% confidence interval [CI], 1.05–3.01; P < .005). SEER data indicated no change in MBC incidence rates (APC, 0.5; NS).
Conclusions: The incidence of MBC in Florida increased significantly between 1985 and 2000. This finding is discordant with SEER incidence data. Further epidemiologic studies are warranted to investigate regional variation.
Key Words: Epidemiology • Incidence • Male breast cancer
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INTRODUCTION
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Male breast carcinoma (MBC) is rare: only 1500 cases are diagnosed in the United States each year.1 Little is known about population-level incidence patterns and regional variation. MBC accounts for <1% of all breast carcinoma, and the lack of sufficient cases makes conducting large-scale prospective clinical trials impractical.2 As a result, clinical management of MBC is guided by research on the disease in females or by data from small case series.3–5 A recent review of the Surveillance, Epidemiology, and End Results (SEER) Program6 data and a large single-institution series revealed no improvement in survival with MBC over the last 25 years.7 Survival rates differ significantly by race/ethnicity: 5-year survival rates are lower for whites and blacks than for men of other race/ethnicity.7 Collection of comprehensive data and identification of high-risk male populations are essential for future improvements in outcome.
Specific aims of this study were to determine (1) the incidence rates of MBC in Florida; (2) the MBC incidence rates in comparison with SEER data; (3) regional variation within Florida; and (4) descriptive information on histopathology and stage at presentation.
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MATERIALS AND METHODS
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Study Population
Study data were obtained from the Florida state cancer registry, the Florida Cancer Data System (FCDS), at the Sylvester Comprehensive Cancer Center of the University of Miami. All males with pathologically confirmed breast carcinoma diagnosed from 1985 through 2000 were included in the study. Sarcomas, lymphomas, and in situ disease were excluded. On the basis of the International Classification of Disease (ICD-O-3)8 coding system, tumors were classified as ductal, lobular, papillary, mucinous, Paget’s, or inflammatory.
MBC was classified by stage with use of the SEER historic stage variable6 for comparative purposes. Stage of disease at diagnosis was defined as local (confined entirely to the breast), regional (extending into regional lymph nodes or into surrounding organs), or distant (spread to remote parts of the body).
For comparison to SEER data, the SEER-9 registries including data from Connecticut, Iowa, Hawaii, New Mexico, Utah, Atlanta, Detroit, San Francisco–Oakland, and Seattle–Puget Sound were evaluated. For control purposes, the incidence rates of male patients with colorectal cancer in Florida were compared with SEER program data to test the uniqueness of FCDS MBC incidence rates.
Statistical Analysis
The primary outcome was age-adjusted incidence. Age-adjusted rates for MBC have been standardized to the U.S. 2000 standard-million population (19 age groups). This allows for comparison of cancer incidence over time and across geographic regions and population subgroups, even when age distributions are not comparable. Age-adjusted rates for incidence were calculated by summing the products of the age-specific rate (for each 5-year age group [0–4, 5–9, etc.]), multiplied by the fraction of the 2000 U.S. population in each age range. Other outcomes included regional incidence, age-specific incidence, descriptive statistics, and annual percent change (APC). The APC is a summary statistic that indicates the trend over a defined time period.9 The APC values were calculated by linear regression to fit a weighted least-squares model to the log of age-adjusted rates for the period. The slope of the line is tested for significant increases or decreases. The most recent 16-year period, 1985 to 2000, was analyzed to give a reliable and current estimate for the APC. Confidence intervals at the 95% level were used to test for statistical significance. Regional populations were divided into seven Florida public health regions: Panhandle, Northeast, North Central, Tampa Bay, South Central, Palm Beach–Broward, and Miami–Dade. Sensitivity analyses were performed.
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RESULTS
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The study period identified 1396 MBC incident cases diagnosed from 1985 through 2000. Table 1 presents the characteristics of the study population. The age of the subjects ranged from 20 to 92, with a mean age of 68 years.
The most common histologic type was ductal (92%), followed mucinous (2%), papillary (2%), and lobular (1%). Inflammatory and Paget’s disease were extremely rare and occurred in only one and 13 cases, respectively.
Stage at diagnosis was as follows: 45%, local; 33%, regional; 7%, distant; and 15%, unstaged. The age-adjusted incidence rate was highest (0.524 per 100,000 males per year) for local stage at presentation (Fig. 1). The age-specific rates were highest in the elderly, with incidence rates at 7.9 and 12.5 per 100,000 in the age groups of 70 to 74 and 85 years, respectively. Treatment included modified radical mastectomy (36%), partial mastectomy with axillary lymph node dissection (18%), simple mastectomy (6%), radical mastectomy (6%), and surgery not otherwise specified (38%).
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FIG. 1. Age-adjusted incidence rates stratified by stage at presentation. Rates are per 100,000 and are age-adjusted to the 2000 U.S. standard population. Stage is defined as local (confined entirely to the breast), regional (extending into regional lymph nodes or into surrounding organs), or distant (spread to remote parts of the body).
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The number of new cases diagnosed increased from 56 in 1985 to 132 in 2000. This represents an overall percent change of 64%. The APC in incidence rates over the 16-year period was 2.0 (95% confidence interval, 1.05–3.01; P < .005). In the SEER program (nine registries) the number of new cases increased from 78 in 1985 to 143 in 2000. The APC remained constant over the same time period (APC, 0.5; NS). Figure 2 compares the age-adjusted change in incidence rates in Florida (FCDS) with SEER data. Incident cases of MBC in the individual nine registries in SEER in comparison with the FCDS are illustrated in Figure 3 for the years 1985 and 2000. Table 2 displays the incidence rates, confidence intervals, and counts per individual registry.
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FIG. 2. The change in age-adjusted incidence rates in the Florida Cancer Data System (FCDS), in comparison with SEER program data. The annual percent change (APC) is statistically significant for Florida (P < .005).
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FIG. 3. Incident cases of MBC in each of the nine SEER individual registries, in comparison with the Florida Cancer Data System (FCDS), 1985–2000. The aging population could account for the higher number of cases in recent years.
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TABLE 2. Male breast cancer age-adjusted incidence rates: Florida compared to individual nine SEER registries, 1985–2000
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Figure 4 depicts the regional variation in incident cases of MBC in Florida, with 28% of new cases diagnosed in Palm Beach–Broward and 18% in South Central regions of Florida.
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FIG. 4. The regional distribution of incident cases of MBC in the seven public health regions of Florida (1985–2000).
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MBC was the only primary cancer in 989 (71%) of the patients. Metachronous primaries were identified in 397 (29%) of patients, and of these primaries, approximately 33% were prostate cancer.
SEER age-adjusted incidence rates for male colorectal cancer were 79 cases per 100,000 in 1985 and 65.2 cases per 100,000 in 2000. Similarly, in Florida, the male age-adjusted incidence rates were 79.1 cases per 100,000 in 1985 and 65.3 per 100,000 cases in 2000.
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DISCUSSION
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We examined the incidence of MBC in a state cancer registry database. The incidence of MBC has significantly increased over the last 16 years in Florida. Age-specific incidence rates show a higher rate in the elderly, especially those over age 70 years. There is also considerable regional variation, with a higher proportion of new cases reported in Palm Beach and Broward Counties and South Central Florida. Factors that may contribute to the rising incidence of MBC include increased awareness secondary to female screening programs, aging of the population, genetics, and changes in the immigrant population.
Germline mutations of the BRCA2 gene are involved in the development of a considerable number of MBC cases.10 Limitations of the FCDS registry preclude analysis of this factor. Recently, cancer susceptibility syndromes have been characterized that suggest possible genetic linkages between breast cancer and prostate cancer within families.11 In a recent series,11 MBC preceded prostate cancer in 80% of cases. In our study, 29% of patients with MBC developed second primaries, and prostate cancer accounted for 33% of this cohort. The incidence of second primaries, specifically prostate cancer, needs to be explored further.
The SEER database is a national population-based registry of cancer data from approximately 15% of the United States (U.S.) population and is thought to be representative of the entire U.S. population. For control purposes, male colorectal cancer cases in Florida were comparable to SEER statistics. Figure 2 displays the incidence of MBC according to SEER data (from nine registries) versus the FCDS data. The FCDS APC for MBC significantly increased over the period of 1985 to 2000. This is disparate from SEER cancer data, which shows no significant change in MBC incidence rates over this time period. Thus, SEER cancer data do not apply to all regions of the country. In order to develop future health care planning directives, accurate tracking of changes in cancer incidence is paramount for targeting high-risk regions.
The reasons for increased regional MBC rates in Florida are unclear. MBCs have been shown to display distinct immunophenotypic differences from those occurring in women, implying a different pathogenesis in the evolution and progression of this disease.12 A case-control study of MBC revealed that positive family history, decreased physical activity, higher body mass index, and increased consumption of vitamin E and calcium were associated with a statistically significant increased risk.13 Environmental toxins such as organochlorine pesticides, including DDT, persist in human tissues for years.14 Further research on the role of environmental factors in the development of MBC is necessary.
This study utilized a large population-based regional cancer data registry, thereby minimizing selection bias. The study also used a large sample for a rare disease. The limitations of this study were lack of data on tumor biomarkers and lack of consistent data on socioeconomic factors, treatment, and screening practices.
The incidence rates of MBC in Florida exhibit a significant regional variation from SEER national data. SEER data are not generalizable to all U.S. populations. With the increasing incidence of MBC, it is imperative that surgeons raise their awareness in the detection and treatment of this cancer. Regional MBC incidence rates need to be further delineated in order to target high-risk populations for future screening and treatment planning.
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FOOTNOTES
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Male breast cancer incidence is increasing in Florida and we report the largest series in an individual state cancer registry. The age-adjusted incidence rates in Florida are discordant from SEER incidence rates.
Received for publication January 6, 2004.
Accepted for publication April 7, 2004.
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ABSTRACT
INTRODUCTION
