Breast Cancer in India: Are we on the verge of an epidemic?
Breast cancer is the leading cancer of women globally. More than ten lakh cases of breast cancer are
diagnosed every year. Large percentage of these cases are from the western world i.e. USA and Europe.
Lifetime risk of breast cancer in western countries is about 11 to 12% that is one in eight to one in nine
women develop breast cancer in their lifetime.
Asian and African countries contributed relatively lesser numbers to the global burden of breast cancer.
However, there is a significant change taking place in Asia in particular and India is also part of this
change. I would like to highlight some of the recorded changes in epidemiology of breast cancer in India
and sensitize to the increasing burden of this problem presently and in future.
In India, cancer burden in women has a major contribution from two sites: uterine cervix and breast.
However, cancer cervix was the leading cancer in all cancer registries previously. In the previous two
decades, there is a dramatic shift in all urban registries. The incidence of breast cancer has been rising
by about 2 to 3% per year. Now, breast cancer is the leading cause of cancer in women in all big urban
areas of India, accounting for more than 25% of all cancers in women. In contrast, cancer cervix is
contributing nearly 20% of cancers in women. The picture is more extreme in bigger metro cities. In
Mumbai, more than 30% of all cancers in women are breast cancers while cancer of uterine cervix
constitutes nearly 13% of all cancers in women.
Why the rising incidence?
Female hormones (estrogens) are supposed to be responsible for the causation of breast cancer.
Lifetime exposure estrogens is an important factor. There are many factors that determine this. Age of
menarche and age of menopause determine the total reproductive life of women. During this period,
estrogen levels are high but vary in a cyclical manner. Pregnancy and lactation are associated with
amenorrhoea and have a protective role. There is approximately 18 months of amenorrhoea with each
pregnancy. In India, fertility patterns are changing rapidly, more so in the urban areas. The rising
incidence that is being seen today is the impact of changes that have taken place two to three decades
earlier. There is further reduction in fertility with many couples having a single child. The effect of this
steep fall in the number of pregnancies and consequent rise in estrogen exposure is likely to manifest
strongly in the coming decades.
Other factors that contribute to a rising incidence of breast cancer including earlier menarche in women
with better nutrition, late marriages and late first childbirth, decreasing trend for breastfeeding and
shorter duration of breastfeeding, use of hormones in the form of oral contraception, postmenopausal
hormone replacement and for other purposes e.g. treatment of infertility, etc.
Another important factor that is contributing to the rising incidence of breast cancer is the rising
incidence of obesity. In postmenopausal women, when ovarian estrogen production has declined
significantly, major part of estrogen is produced in body fat with the action of the enzyme aromatase.
Being overweight leads to higher levels of estrogens in postmenopausal women; and higher incidence of
breast cancer.
Younger age of cancer patients in India!
Another important observation about India is the younger age of women when cancer is diagnosed. In
western countries, a higher percentage of women are more than 50 years of age and are
postmenopausal. In contrast, in India, a large percentage of women are younger than 50 years and
many are younger than 40 years.
It is important to note that younger women have more aggressive cancers that tend to progress rapidly
and are thus more likely to be advanced. Success rate of treatment is lower in younger women.
No clear reasons have been identified for this tendency to have cancer at a younger age in India. One
possible explanation is that overall, India has a younger population and thus more young women are
found among cancer patients. However, there may be other factors that might be leading to an actually
earlier age of onset.
More advanced disease in Indian women!
It is important to point out that breast cancer in Indian women is seen at a more advanced stage in
general. There are many reasons for this. First and foremost, western countries have a population based
screening program for breast cancer that consists of screening mammography at one to two year
interval starting after 40 to 50 years of age. Thus, nearly 60 to 70% of breast cancers in these countries
are either stage 0 or stage I. In contrast, in Indian women, nearly 90% of breast cancers present in stages
that are higher that stage I (i.e. stage II, III and IV).
Screening for breast cancer with mammography needs massive resources in terms of infrastructure for
screening. Further, women who are found to have suspicious lesions on screening mammography need
to have follow up investigations and management. In India, where the government is still struggling with
control of infectious diseases, a screening program for cancer is unlikely in the near future. In addition,
there are controversies related to population based screening in western countries with one particular
concern that screening leads to overdiagnosis. It is also important to point out that screening is more
effective in women above fifty years of age. In India, where large percentage of women have cancers
before fifty years of age, screening may not be as effective.
has increased about Till about two to three decades ago, breast cancer accounted for about one forth
cases of cancers in women and about half cancer related deaths in India. Even in urban areas, cancer of
uterine cervix was still leading the list of cancers in women. But, the scenario is changing rapidly. The
incidence of breast cancer is on rise, especially in Metropolitan cities of India, it has become a leading
cause of cancers in women. In rural areas also, breast cancer is second only to cancer of cervix in
number of newly diagnosed cases. Till the year 1990, all the major population based cancer registries
have reported cervical cancer as the leading cause of cancers in women in India, but by year 2000-2003
the scenario had changed and breast cancer had overtaken as the leading site of cancers in women as
reported in most of the cancer registries. 1. When we study the incidence trends of breast cancer in
India, we come across certain interesting facts. Contrary to Western countries, the peak age of
presentation in our country is between 40-50 years. This means, breast cancer strikes at least two
decades earlier in majority of the patients in India than most of the patients in Western world. Increase
in breast cancer incidence is a global phenomenon. But with increasing incidence there have been
significant improvement in treatment options translating into decreased breast cancer related mortality
in western countries. Unfortunately, the breast cancer outcome data available so far does not show
such promising picture for breast cancer patients of our country.
Age specific incidence curve of breast cancer in urban population of India, as mentioned earlier shows a
steep upward inclination from the age of 35 years to menopausal age then the curve takes a gentle
plateau bend. Incidence of breast cancer in 3rd and 4th decade has been reported to be up to 25%
compared to less than 10% in developed world. Approximately 50% patients present in locally advanced
stage.
This variation in incidence between our country and other western world can
be attributed to many factors. The most important fact is the relatively overall young population of our
country. Other factors can be socioeconomic status, genetic variation, racial/ethnic background, lifestyle
and environmental factors. These differences lead us to think whether breast cancer in Asian
communities should be considered as a biologically different disease compared to western countries.
There is a possibility of certain diverse risk factors which are driving the rising incidence and diseaserelated mortality associated with breast cancer in low income countries. Number of patients with
hormone receptor negative disease is higher in our country compared to western patients. The
difference in mortality is due to limitations in resources which are needed for early detection, diagnosis,
and treatment of the disease. Number of patients presenting in early stages is still very low.
Early menarchy, late menopause, late marriages, late first pregnancy, reduced period of breast feeding,
increased refined fat in diet and reduced physical activity are some of the reasons responsible for
increase in incidence of ca breast.
We
References:
Time Trend in Breast and Cervix Cancer of Women in India, (1990-2003)
Ramnath Takiar and Atul Srivastav
APJCP Issues VOLUME 9, 2008
Issue Number 4 , 777-780
Hence the globally accepted management guidelines need to be modified according to variations in
biological nature of breast cancer in Indian scenario.