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Incidence
In the United States male breast cancer accounts for 1 of every 100
cases of breast cancer, and it represents about 0.2 percent of all malignancies
in men.1 (In women, breast cancer represents 26 percent of all cancers.)
In 1984, approximately 900 in this country will be diagnosed with the disease,
and about 300 will die of breast cancer. 2
In certain parts of the world male breast cancer is more common than in
the United States. Such geographical variances are probably linked to other
disorders endemic to those areas (see section on Risk Factors: Geography,
below). 3
The Male Breast
The breast of the adult male is similar to the breast of a preadolescent
girl.4 It consists primarily of a few branching ducts lined by flattened
cells and surrounded by connective tissue. In girls, these cells and ducts
develop in response to hormones secreted during puberty.
In males, too, breast tissues are capable of responding to hormonal stimulation. Enlargement of the male breast due to growth of the ducts and supporting tissues is known as gynecomastia. Approximately 40 percent of all adolescent boys experience temporary breast enlargement, probably in response to hormones being secreted by the testes. Adolescent gynecomastia typically disappears within a year or two.
In older men the growth of breast tissue can be stimulated by several commonly used drugs and a number of diseases.5 In addition to the hormone estrogen, which is used to treat cancer of the prostate, gynecomastia can be cause by non-hormonal drugs widely prescribed for cardiovascular disorders (digitalis), high blood pressure (reserpine, spironolactone), migraines (ergotamine), and seizures (phenytoin). Gynecomastia can also occur in conjunction with cancer of the testes or the adrenal glands, cirrhosis of the liver, chronic renal dialysis, and a chromosomal disorder known as Klinefelter's syndrome. There is no evidence that forms of gynecomastia that are not estrogen-induced substantially alter the risk of male breast cancer.
The accumulation of fat in obese men can make the breast appear enlarged,
but this is not true gynecomastia.
Cancer of the Male Breast
Almost all breast cancers in men, like most breast cancers in women, are
carcinomas. The most common kind is infiltrating ductal carcinoma, which
accounts for 73 percent of the cancers in men.3 Men can also develop Paget's
disease and inflammatory carcinoma. Various sarcomas may occur, too, although
they are uncommon.
Symptoms of Male Breast Cancer
A painless lump, usually discovered by the patient himself, is by far
the most common first symptom of male breast cancer. Typically the lump
appears beneath the areola, where breast tissue is concentrated.
However, a lump is seldom the only symptom.3 Men are more likely than women to have nipple discharge (sometimes bloody) and sign of local spread, including nipple retraction, fixation to the skin or the underlying tissues, and skin ulceration. About half the men with breast cancer have palpable axillary lymph nodes.3
Most male breast cancers are not large. One study that reviewed a large number of cases found that 51 percent of the tumours were less than 3 centimetres in diameter. The largest, however, measured 28 by 16 centimeters.7
Delayed Diagnosis
The fact that breast cancer in men has often spread locally before it
is diagnosed - even though the small male breast should facilitate early
diagnosis - has been attributed to several factors. Indeed, the very smallness
of the male breast could be a factor. Lacking the bulk of the typical female
breast, even a small carcinoma in a male lies close to the skin above it
and the tissues of the chest wall beneath it. Consequently, the cancer can
more readily invade these nearby structures.8 It has also been suggested
that the location of male tumours, centred around the areola as most of
them are, may facilitate the spread of cancer. Such centrally located tumours
are thought by some to have easy access to internal mammary lymph pathways.
However, many people are unaware that men can develop breast cancer, and neither individual men themselves nor their physicians regularly examine men's breasts. Furthermore, when men discover signs of breast cancer they tend to delay before seeing a physician.8 A 1972 review of cases diagnosed since 1900 showed that men waited 18 months, on the average, before seeking medical advice; for men diagnosed since 1951, this dropped to 10 months,9 such a delay may in part occur because some men perceive breast cancer as a flaw in their masculinity and are reluctant to acknowledge its presence.3
Ethnicity
According to NCI's Surveillance, Epidemiology, and End Results (SEER) Program,
breast cancer affects 14 black men in every million and 8 white men in every
million.10 Some studies have also suggested that the incidence is higher
among Jewish males of European ancestry.
Geography
In Egypt, male breast cancer represents 6 percent of all breast cancers,
and in Zambia it accounts for 15 percent. It has been suggested that one
contributing factor might be an excess of estrogen resulting from scistosomiasis,
a liver disease produced by parasites. Others have proposed a link with
liver disease caused by malnutrition.
Socioeconomic Status
A recent study comparing male breast cancer patients from five metropolitan
areas with men of comparable backgrounds who did not have breast cancer
found that the breast cancer patients were more likely to be college graduates
and employed as professionals or managers.
Heredity
Several researchers have reported two or more cases of male breast cancer
within a single family.3 Several of these reports have involved two brothers;
one involved three brothers; and another described breast cancer in a man,
his father, and his father's brother.
Hormones
Abnormal hormone activity, a factor that has been linked to the development
of female breast cancer, could play a role in the development of male breast
cancer as well. Several disorders with a hormonal component have been associated
with an increased risk of male breast cancer, and numerous studies have
suggested that men with breast cancer display abnormal patterns of hormone
metabolism and excretion.3 In a possibly related finding, one study has
indicated that men with breast cancer married at relatively older ages and
failed to have children.11 In laboratory experiments, it is possible to
produce breast cancer in male mice and rats by means of manipulating hormones.
At the same time, it has long been known that men with breast cancer tend
to respond well to hormone therapy.
Gynecomastia
The relationship between gynecomastia and breast cancer is unclear.3 Some
authors report that as many as 20 percent of the male breast cancer patients
in their studies have a history of gynecomastia.12 Gynecomastia is also
a symptom of Klinefelter's syndrome, a chromosomal disorder that markedly
increases a man's risk of developing breast cancer. Furthermore, gynecomastia
is more common in areas such as Egypt, where malle breast cancer accounts
for a relatively large proportion of the total number of breast cancer cases.
On the other hand, numerous studies have found gynecomastia to be uncommon among breast cancer patients. Moreover, pathologists have identified no clear progression from the cell and tissue changes typical of gynecomastia to the changes characteristic of malignancy.
Klinefelter's Syndrome
Klinefelter's syndrome is a rare disorder characterised by an abnormal chromosome
pattern (XXY), poorly developed sex organs, hormonal abnormalities, and
gynecomastia. Men with this condition are 20 times more likely than the
average man to develop breast cancer.7 They are also more likely to develop
cancer in both breasts, or unusual types of second cancers.
Hormone-Containing Drugs
In the past a number of case reports suggested that estrogens taken to combat
cancer of the prostate (a standard and widely used treatment, which is known
to cause gynecomastia) might also cause male breast cancer. But more recent,
large surveys have indicated that any such effect is very small. One hundred
and fifty urologists surveyed by the American Medical Association identified
on 2 of 17,000 prostate cancer patients treated with estrogens who had developed
breast cancer.13 (Men with prostate cancer, it should be noted, have a shortened
life expectancy, whereas breast cancer may take a long time to develop.)
Breast tumours that do develop in men who have been treated for prostate
cancer may represent metastasis from the prostate cancer rather than a primary
malignancy originating in the breast.3
In very large doses, however, estrogens may be more overtly linked to the development of male breast cancer. Two 20-year-old transsexuals who had sex-change operations, which included surgical castration and breast construction as well as large doses of estrogens, developed cancer within the following 5 years.14
Testicular Disorders
A number of male breast cancer patients have a history of testicular infection
(orchitis), testicular injury, or undescended testis.
Radiation
Radiation exposure, which is associated with an increased incidence of breast
cancer in women, is also thought to play a role in the development of breast
cancer in men. Several cases of male breast cancer have been linked to childhood
radiation for benign disorders of the chest and neck. In one case breast
cancer developed in a man who had been treated for childhood cancer with
both radiation and chemotherapy.15
Trauma
Several studies, especially older ones, suggested that a history of trauma
to the breast preceded the diagnosis of male breast cancer in nearly 30
percent of all cases.16 However, most evidence suggests that nay link is
coincidental, with the trauma perhaps calling attention to a preexisting
tumour.
Diagnosis of Male Breast Cancer
The same procedures used to diagnose breast cancer in women can be used
to diagnose breast cancer in men. These include medical history, physical
examination, mammography, and thermography. As always, a definitive diagnosis
can be made only by biopsy. Karyotyping, a technique used to determine a
patient's chromosome pattern, might be used if a disorder like Klinefelter's
syndrome is suspected. Studies to evaluate estrogen excretion patterns might
also be performed.
In examining a man for breast cancer, a physician must distinguish between a malignant breast tumour and benign conditions, primarily gynecomastia, as well as cancers from other sites that have metastasized to the breast. Metastases to the breast from other types of cancer call for treatment of the primary cancer, whatever it is. Primary breast cancer, in contrast, is potentially curable through surgery and, perhaps, adjuvant therapy.
Unlike gynecomastia, which typically produces a swelling that is firm, well defined, and tender, a malignant breast lump is more likely to be hard, irregular, and painless. In both gynecomastia and breast cancer the lump can adhere to the areola, but a mass due to gynecomastia is not usually fixed to the underlying tissues, nor does it produce ulceration other changes in the nipple and areola. Such changes, as well as skin thickening, inflammation, nipple discharge (especially bloody discharge), and enlarged axillary nodes, are likely to be signs of malignancy. Examination of the testicles sometimes reveals tumours or other testicular lesions that can be responsible for breast enlargement. In general, both youth and bilateral disease favour a diagnosis of gynecomastia.3
Mammography is a useful tool for distinguishing gynecomastia from breast
cancer. On a mammogram gynecomastia tends to look smooth and form a symmetric
cone backward from the nipple, while carcinoma is likely to have an irregular
outline and sometimes looks like it is radiating fine needles.3 Typically
carcinoma is dense, and possibly contains numerous tiny calcifications.6
Staging and Prognosis
A man's prognosis, like a woman's, is influenced by the extent, or stage,
or the disease at the time of diagnosis. Such features as positive axilary
nodes, ulceration or fixation to underlying tissues, large tumour size,
and tumour cells that exhibit highly malignant changes are all signs that
the disease is more likely to have spread. Certain types of male breast
cancer, including intraductal and papillary carcinomas, carry a better than
average prognosis. The prognosis for Page's disease, however, is worse than
the average, whereas in women it is better.
The most important prognosis variable is the status of the axillary nodes. Data from two studies indicate that men with negative nodes experienced 5- and 10-year survivals of 79 percent and 58 percent, respectively. The comparable figures for men with positive nodes were 28 and 6 percent.3
Data from the SEER program found that 58 percent of the 88 men diagnosed
between 1970 and 1973 were classified as having localised disease; 33 percent,
regional disease; and 7 percent, distant spread (2 percent were unknown).
The comparable SEER figures for women were similar - 48, 41,9, and 2 percent,
respectively.10 In one large series of nearly 400 men with breast cancer,
34 percent of the men were classified as Stage I, 14 percent as Stage II,
40 percent as stage III, and 12 percent as Stage IV (Stage I being earliest,
Stage IV most developed). The large proportion of Stage III cases was due
in great part to fixation of the tumour to the skin.3 Preoperative staging
procedures are the same for men as for women. The most useful tests for
detecting distant spread are bone scan and liver function tests.3 Many believe
that breast cancer carries a worse prognosis for men than for women. The
1973 SEER data indicated that 5-year relative survival for all stages of
breast cancer was 65 percent for white men. When the disease was localised,
these figures rose to 85 percent and 66 percent, respectively.10 But data
from numerous recent studies differ, and they are difficult to compare with
earlier figures since the studies may involve small numbers, use differing
criteria, or rely on pooled data. Some show marked differences in survival
between men and women, others show none. In general, when the figures are
adjusted to take into account the fact that more men than women are dying
from unrelated causes (in part related to their older average age), male-female
differences diminish. Overall, women may have a survival advantage, but
it is slight.3
Hormone Receptor Assays
Breast tumour tissues contain hormone receptors in a high proportion of
men - over 80 percent,18 compared to about 65 percent in women. This discrepancy
correlates well with the fact that more men than women with breast cancer
- two-thirds versus one-third - respond to hormonal therapy.3 Biopsy specimens
from gynecomastia, unlike breast cancer tissue, tend to contain low levels
of hormone receptors.19 Hormone receptors now play an important role in
selecting the proper treatment for women with breast cancer, but it is not
yet known how important they will prove in treating male breast cancer.
Preliminary evidence suggests that very low levels of hormone receptors
might correspond to a poor response to hormone therapy.19,20 If this proves
true, hormone receptor assays could be useful in identifying those few men
with advanced disease who will not benefit from ablative or additive hormonal
therapy. It is not known if hormone receptor status indicates in men, as
it can in women, a good prognosis.
Surgery
Mastectomy, or surgical removal of the breast, is the standard treatment
for male breast cancer, and is used in approximately 80 percent of all cases.
Radical mastectomy is used most frequently, although in men a skin graft
is often needed to close the wound. Simple mastectomy has been used either
when prognosis is good, for patients with very limited disease, or when
prognosis is poor, for patients deemed too old or too ill for more extensive
surgery.8
Radiation
Primary radiation therapy has sometimes been used to treat men with Stage
I cancer who were not otherwise strong enough to tolerate anaesthesia and
surgery. More often radiotherapy alone has been used to relieve symptoms
in patients with disease too advanced for potentially curative surgery.
Men with breast cancer are often treated with postoperative adjuvant radiation
therapy, but the extent to which this procedure improves survival is not
known.3 A recent review concluded that limited surgery coupled with postoperative
irradiation affords good disease control.21
Adjuvant Chemotherapy
The decision to use adjuvant chemotherapy to treat men with breast cancer
must be made on an individual basis. In women, such prophylactic systemic
therapy has apparently benefited patients who have no signs of distant metastasis
but who have positive axillary lymph nodes. The disadvantages of giving
toxic drugs, especially to older patients, must be weighed against the high
rate of recurrence for men with positive nodes.3
Ablative Hormone Therapy
For 40 years it has been known that, in a substantial portion of men with
advanced breast cancer, surgery to remove the testes (orchiectomy) can cause
tumours to shrink,metastases to clear up, and symptoms to disappear, for
periods lasting from months to years. More recently, similar results have
been achieved by removal of the adrenal glands (adrenalectomy) and the pituitary
gland (hypophysectomy).12 Orchiectomy, or surgical castration, is usually
the initial ablative procedure because it produces a high response rate
with few surgical complications. Men who respond to orchiectomy as well
as those who fail to do so may respond subsequently to either adrenalectomy
or hypophysectomy,12 and these operations can be used sequentially.
One large review established that orchiectomy produced tumour regression
in two-thirds of the men treated; the median response lasted 22 months.
Adrenalectomy led to a response in three-fourths of the patients, which
lasted for a median period of 26 months. Hypophysectomy succeeded in more
than half of the men, with responses lasting for a median duration of 20
months.12 These therapies not only produced tumour regression and relief
of symptoms, but they also lengthened the responders' survival.
Additive Hormone Therapy
Several reports have suggested that additive hormone therapy, which is so
widely used in women, is of little value in treating male breast cancer.12
Other reports, however, particularly from European centres, indicate that
hormones such as the synthetic estrogen, diethylstilbestrol (DES), can be
effective. For example, on study found that DES produced long remissions
(a median of 60 months) in nearly two-thirds of the men with metastases
to soft tissue sites such as skin and lymph nodes; however, no patients
with bone metastases responded.23 Some men with breast cancer have also
responded to progesterone.24
Antiestrogens
To date, only a few men with breast cancer have been treated with the antiestrogen
drug, tamoxifen. Initial results indicate that tamoxifen will produce remissions
in nearly half of those men treated.25
Chemotherapy
Although few men have been treated for advanced breast cancer with chemotherapeutic
agents, in one series 18 men were given a variety of drugs. For the most
part, they received one drug at a time, not combinations. The overall response
rate was 44 percent, and all types of metastases responded.22 In view of
the fact that endocrine therapy benefits so many men, chemotherapy is likely
to play a secondary role in advanced male breast cancer. However, in the
future, estrogen receptor status could help identify men less likely to
respond to hormone manipulations. For them, chemotherapy might be the more
appropriate treatment.5
Rehabilitation
Little has been written about the psychosocial problems that men face in
adjusting to breast cancer. In addition to the types of feelings that beset
other cancer patients, a man who has breast cancer is confronted with several
special challenges. To begin with, the rarity of his condition could leave
him feeling particularly alone and helpless, especially if his physician
has seldom or never treated the disorder before. Second, having a disease
that is predominantly female, and one that involves hormone imbalances,
might be seen as a threat to the patient's masculinity. The problem is further
complicated if the patient must undergo surgical castration or take feminizing
estrogens. Finally, loss of arm strength following radical mastectomy can
incapacitate a man whose work or recreation involves physical activity.
Future Considerations
The small numbers of men who develop breast cancer make it unlikely that
large prospective trials can ever be undertaken to compare various therapies.
However, it is possible that institutions that see more than the usual number
of cases could collaborate in building up a fund of reliable information.26
In the meantime, it is important that individual physicians and surgeons
keep careful records to document the cases of the several hundred men who
develop breast cancer each year in the United States.
To improve the prognosis of male breast cancer, broader efforts are needed
to let men know that the disease exists and that, like other cancers, it
can be cured or controlled if it is diagnosed and treated promptly.
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