Insulin is important for the regulation of blood sugar in our body. People who are obese have a higher incidence of developing type II diabetes. Although these individuals have a higher level of insulin in their blood, the blood sugar is still elevated because the cells in the body are ‘resistant’ to the insulin action. Obese women are known to have a higher incidence of breast cancer. The higher oestrogen level in these women has been shown to play a significant role in causing breast cancers. Does the excess insulin in these obese women play a role too?

Researchers from US assessed the association between circulating insulin level and the risk of breast cancer in non-diabetic women (J Natl Cancer Inst 2009; 101: 48 – 60). Women enrolled in the Women’s Health Initiative Observational Study (WHI-OS) were studied: 835 women with incident breast cancer and 816 women without breast cancer. Women with the highest insulin levels, when compared to those with the lowest levels, were 46% more likely to develop breast cancer. Among women who did not use hormonal therapy (HT), the risk of developing breast cancer in women with the highest vs lowest insulin levels was increased 2.4 times. Obesity (where BMI ≥ 30), among non-HT users, was also associated with the risk of breast cancers. If your BMI is ≥ 30, your risk of developing breast cancer is 2.12 times more than someone whose BMI is 18.5 to < 25.

In laboratory studies, insulin has been shown to be a mitogen. (A mitogen is a factor which can cause cells to divide.) The above study showed that too much insulin exerts a deleterious effect on breast tissue. Obese individuals, both men and women, have higher circulating levels of oestrogen and insulin. In women, elevated levels of oestrogen and insulin are thought to be responsible for the increased breast cancer risk. In men, the elevated oestrogen and insulin levels have not been linked with specific cancers yet. However, it would not be unreasonable to speculate that it is only a matter of time before a causal relationship with some cancer is found.

This is the beginning of a new year and traditionally it is time to make a resolution. Many have made unrealistic goals and thus fail to fulfill their wishes. Losing weight should be done gradually. If you go on a crash course, starve yourself and lose 3 kg over a week, the bulk of the weight loss would be from muscle. When you put on weight later on, the gain is more in the form of fat.

As this is the start of a new year, do start with your resolution but do not be impatient. Losing weight and staying trim requires a long term commitment. Like many good things in life, it takes time.

The relationship between caffeine consumption and breast cancer has been a point of contention for a while. While most studies have not shown an association, several have shown an inverse relation or a weak positive association. Two recent studies from the United States have further examined this relationship.

The first study from the Brigham and Women’s Hospital took detailed dietary information from 38,432 women who were 45 years or older and were free from cancer during the period 1992 – 1995 (Arch Intern Med 2008; 168: 2022 – 2031). These women were followed up for a mean period of 10 years. Women who almost never drank coffee and those who drank 4 or more cups of coffee daily did not show an increased risk of developing breast cancer. The same findings were seen in women who drank tea (≥ 2 cups daily vs almost never). However, the study did find a borderline significant positive association with breast cancer risk in women with existing benign breast disease who consumed the most amount of caffeine and coffee. The study also found a significant association between caffeine consumption and the risk of developing estrogen and progesterone receptor-negative breast cancer (68% more likely) and breast tumours larger than 2 cm (79% more likely).

In another report from the Harvard School of Public Health, 85,987 female participants in the Nurses’ Health Study were followed up for 22 years (Int J Cancer 2008; 122: 2071 – 2076). Their consumption of coffee, tea and caffeine consumption was assessed in 1980, 1984, 1986, 1990, 1994, 1998 and 2002. Women who consumed ≥ 4 cups of coffee / day did not have an increased risk of developing breast cancer. Similarly, intake of tea and decaffeinated coffee was not associated with breast cancer risk. However, in postmenopausal women, an inverse association was found. There was a 12% difference in the risk of breast cancer for the highest intake group compared to the lowest intake group.

While these two big studies have shown that caffeine in general is not associated with risk of breast cancers, too much caffeine can be bad for a sub-set of women. If you were to develop breast cancer, caffeine consumption may give rise to poorer tumour characteristics. While this is not confirmed beyond reasonable doubt, it might be prudent for you to remember the saying ‘Everything in moderation please’ while the jury is still out.

Breast cancer is a major killer world wide. In USA it is the most common non-skin cancer and the second leading cause of cancer-related deaths in women. Approximately 500,000 deaths worldwide are related directly or indirectly to breast cancer. Presently mammography is used extensively for breast screening and is effective in picking up breast cancer at an earlier stage, thus, decreasing the mortality rates from breast cancer. While mammography is highly effective in detecting breast cancer, it is not foolproof. With the advent of MRI, instead of using mammography, some patients are requesting MRI to screen for breast cancer. Is this wise?

While MRI has a high sensitivity in detecting breast abnormality, it has a low specificity. In other words, MRI can over diagnose and give you more reading of ‘cancer’ when the actual abnormal appearance on the scan is not due to cancer. In high-risk groups, such as women with breast cancer gene (BRCA) mutations, MRI is likely to be more sensitive than mammography, ultrasound and clinical breast examination in detecting breast cancer earlier. The reasons for this are that BRCA1-associated breast cancers are more likely to have round, pushing margins and rare calcifications and other benign mammographic appearances. Childhood cancer survivors are another group of high-risk individuals who might benefit from MRI because these individuals have dense breast tissue which makes mammographic assessment more difficult. It is a challenge for doctors to detect early breast cancer in breasts augmented with silicone because cancerous changes may be misinterpreted as silicone-induced mastopathy. MRI is good for differentiating between cancerous changes and silicone induced nodularity.

In patients with axillary lymphadenopathy (swollen lymph glands in the armpit) due to an occult breast cancer (non-palpable and non-mammographically visible), MRI can help to detect a suspicious breast lesion. Sixty percent of patients with ductal carcinoma in situ (DCIS) may develop invasive breast cancer over a period of 10 years. In a German study involving 7000 women who were subjected to mammography and MRI over a 5-year period, MRI detected significantly more cases (92%) of any grade of DCIS than mammography (56%). The study found that MRI is better in diagnosing DCIS, especially those with high-grade DCIS (Lancet 2007; 370: 485 – 492). However, it must be emphasized that the role of MRI in DCIS is not fully established.

At the recent 92^nd Clinical Congress of the American College of Surgeons, it was stated that breast MRI is an essential tool in screening high-risk groups, assessing the extent of disease and follow-up. MRI also has a role in cases of unknown primary tumour and in assessing the response to chemotherapy. The American Cancer Society recommends a screening MRI for women who have 20 – 25% or greater lifetime risk of breast cancer, including those with a strong family history of breast or ovarian cancer and those treated for Hodgkin’s disease (CA Cancer J Clin 2007; 57: 75 – 89).

Like all high tech medical tools, MRI of the breast is not applicable to everyone. It has limitations and requires clear guidelines as to when it should be used. When used judiciously, MRI is invaluable in guiding the doctors in managing a case of breast cancer. When used inappropriately, MRI can over-diagnose breast cancer in someone without breast cancer, giving rise to unnecessary anxiety and worse still causing someone to undergo an unnecessary and potentially disfiguring operation. 

(For those interested in reading a recent review article on the role of MRI in screening, diagnosis and management of breast cancer, please consult Expert Rev Anticancer Ther 2008; 8: 811 – 817)