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, according to new research funded by the charity Breast Cancer Now and published in Breast Cancer Research. The study is one of the largest ever into male breast cancer, enabling the team to show a highly statistically significant association.
A link with infertility had been suspected, since parity markedly reduces the risk of female breast cancer; there are known genetic links in both sexes, and a high risk of both breast cancer and infertility among men with Klinefelter syndrome, suggesting some sex hormone-related involvement. However, the rarity of breast cancer in men – with an annual incidence of about 370 cases and 80 deaths per year in the United Kingdom – meant that past studies were necessarily small and yielded mixed results.
“Compared with previous studies, our study of male breast cancer is large,” said study coauthor Michael Jones, PhD, of the division of genetics and epidemiology at the Institute of Cancer Research (ICR) in London. “It was carried out nationwide across England and Wales and was set in motion more than 15 years ago. Because of how rare male breast cancer is, it took us over 12 years to identify and interview the nearly 2,000 men with breast cancer who were part of this study.”
The latest research is part of the wider Breast Cancer Now Male Breast Cancer Study, launched by the charity in 2007. For the new study, the ICR team interviewed 1,998 males living in England and Wales who had been diagnosed with breast cancer between 2005 and 2017. All were aged under 80 but most 60 or older at diagnosis; 92% of their tumors were invasive, and almost all were estrogen receptor positive (98.5% of those with known status).
Their responses were compared with those of a control group of 1,597 men without breast cancer, matched by age at diagnosis and geographic region, recruited from male non-blood relatives of cases and from husbands of women participating in the Generations cohort study of breast cancer etiology.
Raised risk with history of male infertility
Overall, 112 cases (5.6%) and 80 controls (5.0%) reported that they had had infertility problems for which they or their partner had consulted a doctor or infertility clinic. This represented a raised odds ratio of 1.29 (95% confidence interval, 0.94-1.77), which was statistically not significant. However, when analyzed by outcome of the infertility consultation, there was a significant and more than doubled risk of breast cancer among men who were diagnosed as the source of the couple’s infertility (OR = 2.03 [1.18-3.49]), whereas this was not the case among men whose partner was the source (OR = 0.86 [0.51-1.45]) or for whom no source was identified (OR = 1.26 [0.71-2.24]).
In addition, proportionately fewer cases (1,615, or 80.8%) compared with controls (1,423, or 89.1%) had fathered any children, also giving a statistically significantly raised risk of breast cancer for men with no biological children (OR = 1.50 [1.21-1.86], P < .001), “congruent with infertility as a risk factor,” the authors said. The risk was statistically significant for invasive tumors but not for the much smaller number of in situ tumors.
Analysis by number of children showed a decreasing risk with increasing numbers of children, with a highly significant (P < .001) inverse trend where zero was included as a value, but a borderline significant trend (P = .04) if it was not. The team noted that number of children beyond one is difficult to interpret as an indicator of male fertility, since it may more reflect social and cultural factors than fertility per se.
Baseline demographic factors were adjusted for in the risk analyses, and results were not materially changed by sensitivity analyses adjusting additionally for alcohol consumption, smoking, liver disease, and family history of breast cancer. The association also largely remained after exclusion of patients with other preexisting potential confounders including severe obesity and testicular abnormalities, and was consistent irrespective of HER-2 status (there were too few ER-negative tumors to analyze results by ER status).
Potential underlying factors
“The causes of breast cancer in men are largely unknown, partly because it is rare and partly because previous studies have been small,” Dr. Jones said. “The evidence presented in our study suggests that the association of infertility and breast cancer should be confirmed with further research, and future investigations are needed into the potential underlying factors, such as hormone imbalances.”
Commenting on the study, Fiona Osgun, senior health information manager at Cancer Research UK, told this news organization: “Overall, there isn’t strong evidence that infertility is a risk factor for male breast cancer. This study helps to shed light onto a cancer type that is sadly still not very well understood, but much more research is needed to say that infertility is a risk factor for male breast cancer.”
She added that although male breast cancer is a rare condition, it’s still important for men to be aware of what looks and feels normal for them, and to be encouraged to seek medical advice if something is not quite right.
A spokesperson for Breast Cancer UK told this news organization: “[We] believe it’s important to understand what leads to breast cancer in men as well as women and that high quality, long-term studies such as this will help with this understanding.
The findings are consistent with an earlier study that found that U.S. men who have never fathered children are at higher risk of breast cancer. This new long-term U.K. study provides strong evidence, which supports this finding.
“As the authors note, the biological reasons are unclear, but may be associated with altered hormone levels. The ratio of circulating levels of estrogen and androgens (e.g. testosterone) is crucial in healthy functioning of breast tissue. Disruption to this, for example as a result of damage to testes, may affect both fertility and breast cancer risk.
“It is also possible that external factors, such as exposure to certain endocrine (hormone) disrupting chemicals (EDCs), which affect sex hormones, may also affect both fertility and breast cancer risk.
“More studies into breast cancer in men are needed to help us understand better all the risk factors associated with this disease including both hormonal factors and chemical exposures.”
Simon Vincent, PhD, director of research, support, and influencing at Breast Cancer Now, said: “Research has discovered different treatments directed at some features of breast cancer in women; however, breast cancer is not as well understood for men. This is why Breast Cancer Now funds the Male Breast Cancer Study, which looks at what might cause the disease in men. Discovering a link between infertility and male breast cancer is a step towards us understanding male breast cancer and how we could find more ways to diagnose and treat men – and possibly women – with this devastating disease.”
A version of this article first appeared on Medscape UK.
, according to new research funded by the charity Breast Cancer Now and published in Breast Cancer Research. The study is one of the largest ever into male breast cancer, enabling the team to show a highly statistically significant association.
A link with infertility had been suspected, since parity markedly reduces the risk of female breast cancer; there are known genetic links in both sexes, and a high risk of both breast cancer and infertility among men with Klinefelter syndrome, suggesting some sex hormone-related involvement. However, the rarity of breast cancer in men – with an annual incidence of about 370 cases and 80 deaths per year in the United Kingdom – meant that past studies were necessarily small and yielded mixed results.
“Compared with previous studies, our study of male breast cancer is large,” said study coauthor Michael Jones, PhD, of the division of genetics and epidemiology at the Institute of Cancer Research (ICR) in London. “It was carried out nationwide across England and Wales and was set in motion more than 15 years ago. Because of how rare male breast cancer is, it took us over 12 years to identify and interview the nearly 2,000 men with breast cancer who were part of this study.”
The latest research is part of the wider Breast Cancer Now Male Breast Cancer Study, launched by the charity in 2007. For the new study, the ICR team interviewed 1,998 males living in England and Wales who had been diagnosed with breast cancer between 2005 and 2017. All were aged under 80 but most 60 or older at diagnosis; 92% of their tumors were invasive, and almost all were estrogen receptor positive (98.5% of those with known status).
Their responses were compared with those of a control group of 1,597 men without breast cancer, matched by age at diagnosis and geographic region, recruited from male non-blood relatives of cases and from husbands of women participating in the Generations cohort study of breast cancer etiology.
Raised risk with history of male infertility
Overall, 112 cases (5.6%) and 80 controls (5.0%) reported that they had had infertility problems for which they or their partner had consulted a doctor or infertility clinic. This represented a raised odds ratio of 1.29 (95% confidence interval, 0.94-1.77), which was statistically not significant. However, when analyzed by outcome of the infertility consultation, there was a significant and more than doubled risk of breast cancer among men who were diagnosed as the source of the couple’s infertility (OR = 2.03 [1.18-3.49]), whereas this was not the case among men whose partner was the source (OR = 0.86 [0.51-1.45]) or for whom no source was identified (OR = 1.26 [0.71-2.24]).
In addition, proportionately fewer cases (1,615, or 80.8%) compared with controls (1,423, or 89.1%) had fathered any children, also giving a statistically significantly raised risk of breast cancer for men with no biological children (OR = 1.50 [1.21-1.86], P < .001), “congruent with infertility as a risk factor,” the authors said. The risk was statistically significant for invasive tumors but not for the much smaller number of in situ tumors.
Analysis by number of children showed a decreasing risk with increasing numbers of children, with a highly significant (P < .001) inverse trend where zero was included as a value, but a borderline significant trend (P = .04) if it was not. The team noted that number of children beyond one is difficult to interpret as an indicator of male fertility, since it may more reflect social and cultural factors than fertility per se.
Baseline demographic factors were adjusted for in the risk analyses, and results were not materially changed by sensitivity analyses adjusting additionally for alcohol consumption, smoking, liver disease, and family history of breast cancer. The association also largely remained after exclusion of patients with other preexisting potential confounders including severe obesity and testicular abnormalities, and was consistent irrespective of HER-2 status (there were too few ER-negative tumors to analyze results by ER status).
Potential underlying factors
“The causes of breast cancer in men are largely unknown, partly because it is rare and partly because previous studies have been small,” Dr. Jones said. “The evidence presented in our study suggests that the association of infertility and breast cancer should be confirmed with further research, and future investigations are needed into the potential underlying factors, such as hormone imbalances.”
Commenting on the study, Fiona Osgun, senior health information manager at Cancer Research UK, told this news organization: “Overall, there isn’t strong evidence that infertility is a risk factor for male breast cancer. This study helps to shed light onto a cancer type that is sadly still not very well understood, but much more research is needed to say that infertility is a risk factor for male breast cancer.”
She added that although male breast cancer is a rare condition, it’s still important for men to be aware of what looks and feels normal for them, and to be encouraged to seek medical advice if something is not quite right.
A spokesperson for Breast Cancer UK told this news organization: “[We] believe it’s important to understand what leads to breast cancer in men as well as women and that high quality, long-term studies such as this will help with this understanding.
The findings are consistent with an earlier study that found that U.S. men who have never fathered children are at higher risk of breast cancer. This new long-term U.K. study provides strong evidence, which supports this finding.
“As the authors note, the biological reasons are unclear, but may be associated with altered hormone levels. The ratio of circulating levels of estrogen and androgens (e.g. testosterone) is crucial in healthy functioning of breast tissue. Disruption to this, for example as a result of damage to testes, may affect both fertility and breast cancer risk.
“It is also possible that external factors, such as exposure to certain endocrine (hormone) disrupting chemicals (EDCs), which affect sex hormones, may also affect both fertility and breast cancer risk.
“More studies into breast cancer in men are needed to help us understand better all the risk factors associated with this disease including both hormonal factors and chemical exposures.”
Simon Vincent, PhD, director of research, support, and influencing at Breast Cancer Now, said: “Research has discovered different treatments directed at some features of breast cancer in women; however, breast cancer is not as well understood for men. This is why Breast Cancer Now funds the Male Breast Cancer Study, which looks at what might cause the disease in men. Discovering a link between infertility and male breast cancer is a step towards us understanding male breast cancer and how we could find more ways to diagnose and treat men – and possibly women – with this devastating disease.”
A version of this article first appeared on Medscape UK.
, according to new research funded by the charity Breast Cancer Now and published in Breast Cancer Research. The study is one of the largest ever into male breast cancer, enabling the team to show a highly statistically significant association.
A link with infertility had been suspected, since parity markedly reduces the risk of female breast cancer; there are known genetic links in both sexes, and a high risk of both breast cancer and infertility among men with Klinefelter syndrome, suggesting some sex hormone-related involvement. However, the rarity of breast cancer in men – with an annual incidence of about 370 cases and 80 deaths per year in the United Kingdom – meant that past studies were necessarily small and yielded mixed results.
“Compared with previous studies, our study of male breast cancer is large,” said study coauthor Michael Jones, PhD, of the division of genetics and epidemiology at the Institute of Cancer Research (ICR) in London. “It was carried out nationwide across England and Wales and was set in motion more than 15 years ago. Because of how rare male breast cancer is, it took us over 12 years to identify and interview the nearly 2,000 men with breast cancer who were part of this study.”
The latest research is part of the wider Breast Cancer Now Male Breast Cancer Study, launched by the charity in 2007. For the new study, the ICR team interviewed 1,998 males living in England and Wales who had been diagnosed with breast cancer between 2005 and 2017. All were aged under 80 but most 60 or older at diagnosis; 92% of their tumors were invasive, and almost all were estrogen receptor positive (98.5% of those with known status).
Their responses were compared with those of a control group of 1,597 men without breast cancer, matched by age at diagnosis and geographic region, recruited from male non-blood relatives of cases and from husbands of women participating in the Generations cohort study of breast cancer etiology.
Raised risk with history of male infertility
Overall, 112 cases (5.6%) and 80 controls (5.0%) reported that they had had infertility problems for which they or their partner had consulted a doctor or infertility clinic. This represented a raised odds ratio of 1.29 (95% confidence interval, 0.94-1.77), which was statistically not significant. However, when analyzed by outcome of the infertility consultation, there was a significant and more than doubled risk of breast cancer among men who were diagnosed as the source of the couple’s infertility (OR = 2.03 [1.18-3.49]), whereas this was not the case among men whose partner was the source (OR = 0.86 [0.51-1.45]) or for whom no source was identified (OR = 1.26 [0.71-2.24]).
In addition, proportionately fewer cases (1,615, or 80.8%) compared with controls (1,423, or 89.1%) had fathered any children, also giving a statistically significantly raised risk of breast cancer for men with no biological children (OR = 1.50 [1.21-1.86], P < .001), “congruent with infertility as a risk factor,” the authors said. The risk was statistically significant for invasive tumors but not for the much smaller number of in situ tumors.
Analysis by number of children showed a decreasing risk with increasing numbers of children, with a highly significant (P < .001) inverse trend where zero was included as a value, but a borderline significant trend (P = .04) if it was not. The team noted that number of children beyond one is difficult to interpret as an indicator of male fertility, since it may more reflect social and cultural factors than fertility per se.
Baseline demographic factors were adjusted for in the risk analyses, and results were not materially changed by sensitivity analyses adjusting additionally for alcohol consumption, smoking, liver disease, and family history of breast cancer. The association also largely remained after exclusion of patients with other preexisting potential confounders including severe obesity and testicular abnormalities, and was consistent irrespective of HER-2 status (there were too few ER-negative tumors to analyze results by ER status).
Potential underlying factors
“The causes of breast cancer in men are largely unknown, partly because it is rare and partly because previous studies have been small,” Dr. Jones said. “The evidence presented in our study suggests that the association of infertility and breast cancer should be confirmed with further research, and future investigations are needed into the potential underlying factors, such as hormone imbalances.”
Commenting on the study, Fiona Osgun, senior health information manager at Cancer Research UK, told this news organization: “Overall, there isn’t strong evidence that infertility is a risk factor for male breast cancer. This study helps to shed light onto a cancer type that is sadly still not very well understood, but much more research is needed to say that infertility is a risk factor for male breast cancer.”
She added that although male breast cancer is a rare condition, it’s still important for men to be aware of what looks and feels normal for them, and to be encouraged to seek medical advice if something is not quite right.
A spokesperson for Breast Cancer UK told this news organization: “[We] believe it’s important to understand what leads to breast cancer in men as well as women and that high quality, long-term studies such as this will help with this understanding.
The findings are consistent with an earlier study that found that U.S. men who have never fathered children are at higher risk of breast cancer. This new long-term U.K. study provides strong evidence, which supports this finding.
“As the authors note, the biological reasons are unclear, but may be associated with altered hormone levels. The ratio of circulating levels of estrogen and androgens (e.g. testosterone) is crucial in healthy functioning of breast tissue. Disruption to this, for example as a result of damage to testes, may affect both fertility and breast cancer risk.
“It is also possible that external factors, such as exposure to certain endocrine (hormone) disrupting chemicals (EDCs), which affect sex hormones, may also affect both fertility and breast cancer risk.
“More studies into breast cancer in men are needed to help us understand better all the risk factors associated with this disease including both hormonal factors and chemical exposures.”
Simon Vincent, PhD, director of research, support, and influencing at Breast Cancer Now, said: “Research has discovered different treatments directed at some features of breast cancer in women; however, breast cancer is not as well understood for men. This is why Breast Cancer Now funds the Male Breast Cancer Study, which looks at what might cause the disease in men. Discovering a link between infertility and male breast cancer is a step towards us understanding male breast cancer and how we could find more ways to diagnose and treat men – and possibly women – with this devastating disease.”
A version of this article first appeared on Medscape UK.
FROM BREAST CANCER RESEARCH