Detecting Breast Cancer in Women with Dense Breasts Made Easier

Valley of the Kings, located on the west bank of the Nile, Egypt. (Dr. Noorali Bharwani)
Valley of the Kings, located on the west bank of the Nile, Egypt. (Dr. Noorali Bharwani)

The Canadian Cancer Society recommends that all women 50 to 69 years of age be screened for breast cancer every two years, using mammography. But mammography is less useful in identifying cancerous tissue in women with dense breasts; that is, women whose breasts have less fatty tissue but have more fibrous tissue.

In Canada, more than one million women (that is 50 per cent of women) who are 50 to 69 years old have dense breasts. Mammography is not a good test for picking up breast cancer in women with dense breasts. These women are being offered an additional test in the U.S. at a cost of about U.S. $2000 (two thousand). This test is called molecular breast imaging (MBI). This is not the first line of investigation for breast lumps. All women who are eligible for breast screening first undergo mammography and if necessary ultrasound to see if a lump is solid or cystic. Women with dense breasts then can be offered MBI if the mammogram is negative.

In a study from Mayo Clinic, 2600 women with dense breasts underwent mammogram and then MBI. Thirty two per cent of women were found to have breast cancer. Of these only eight breast cancers were picked-up by mammogram alone but 29 breast cancers were picked up by mammography plus MBI. This test is four times better than mammogram alone, is less painful and gives better pictures. However, this is not the final answer. More research is in progress to see how the results can be improved.

MBI is not going to replace mammography. Mammograms will remain the gold standard in breast cancer screening and will continue to be the standard first step in breast cancer detection. Use of MBI, MRI (magnetic resonance imaging) and ultrasound will continue to serve special populations of patients who need tests beyond a mammography.

Breast MRI is not recommended as a screening tool for women who are at average risk of developing breast cancer. It is better than mammogram but a major disadvantage is that breast MRI screening results in more false positives. In other words, the test finds something that initially looks suspicious but turns out not to be cancer. To avoid unnecessary biopsies MRI screening is reserved for high-risk women only. MRI is also more expensive and not widely available.

In conclusion, mammograms are probably the most important tool doctors have, not only to screen for breast cancer, but also to diagnose, evaluate, and follow people who’ve had breast cancer. It is safe and reasonably accurate. The technique has been in use for more than 50 years. MBI is still being tested, but it appears to hold promise for detecting breast cancer in women who are at higher-than-average risk for the disease and have dense breasts. Ultrasound and MRI is used for special cases.

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Screening with Pap Test Should Not be Ignored

Barbuda - time to relax on a beach. (Dr. Noorali Bharwani)
Barbuda - time to relax on a beach. (Dr. Noorali Bharwani)

“The rate of death from cervical cancer is reduced by more than 80 per cent among women who have regular Papanicolaou (Pap) screening,” says an article in the Canadian Medical Association Journal (CMAJ December 9, 2014).

Every woman knows or should know the importance of regular Pap smear test. Since World War II, the test has been the most widely used and successful cancer screening technique in history. It is named after the Greek doctor who invented it – Dr. George Nicholas Papanicolaou.

Since the Pap smear was introduced in 1940s, deaths from invasive cervical cancer occur mostly among women who do not undergo regular screening. It is sad to note that women of lower socioeconomic status and those who are older, First Nations or immigrants are less likely to be screened regularly.

The article notes that screening intervals shorter than three years increase the risk of finding and investigating abnormalities that mostly resolve spontaneously. So it is unnecessary to do Pap smear more often than every three years. The drawback is that longer intervals require organized screening and recall programs to maintain high participation rates. This is not always easy.

At what age should we start doing Pap smear? This varies by jurisdiction, but most guidelines agree that harm from false-positive results outweighs potential benefits of Pap screening in young women. Women who have had a total hysterectomy for a benign disorder and women over 70 years of age who have had three normal test results within 10 years do not require Pap screening, says the article.

Choosing Wisely Canada recommendations on Pap screening are as follows:
1. Don’t use the Pap test for screening in women who are under 21 or more than 69 years of age (Screening should stop at age 70 if the results of three previous tests were normal).
2. Don’t do Pap screening annually in women with previously normal results.
3. Don’t do Pap tests in women who have had a full hysterectomy for a benign disorder.

How can we prevent cervical cancer by testing for human papillomavirus (HPV) infection? The answer to this question is not clear yet. It is work in progress. It is important to remember that HPV is a cancer-causing virus. We know infection with specific strains of HPV is a necessary precursor to cervical cancer. HPV types 16 and 18 are present in about 70 per cent of cervical cancers worldwide and are targeted in HPV vaccines. Some of the viruses cause genital warts – another sexually transmitted infection.

Who is susceptible to HPV infection? A woman who is sexually active, she has multiple partners or she has sexually transmitted infection. Then there would be an indication to do HPV test. The reason HPV test is not recommended for all women is because there is not yet sufficient data on its effect on mortality and incidence of invasive cervical cancer.

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Significance of BRCA genes in ovarian cancer.

International symbol of breast cancer awareness. (iStockphoto)
International symbol of breast cancer awareness. (iStockphoto)

First, it was Angelina Jolie, who had a double mastectomy because of increased genetic risk of breast cancer due to the presence of BRCA gene. The presence of BRCA gene also increases the risk of ovarian cancer. We know that if you have a family history of ovarian cancer then the risk of ovarian cancer increases amongst women in that family.

Take for example the recent announcement that Pierce Brosnan’s daughter Charlotte Emily died of ovarian cancer at age 42. Brosnan is a former James Bond star whose first wife, Cassandra (Charlotte’s mother), was also killed by the same disease in 1991 when she was 43. I am not sure if Charlotte Emily’s BRCA status is known.

There are two types of BRCA genes known as BRCA1 and BRCA2. BRCA is an abbreviation for breast cancer. These genes are tumour suppressor genes and once they undergo changes (mutation), their capacity to normally prevent cancer from developing is lost. It is now known that women found to have mutations in the genes have a very high risk of developing breast and ovarian cancers.

The genetic mutations are not common. About one in 500 to one in 1,000 individuals will carry a mutation or a gene change in one or another of these genes. It generally occurs amongst people who tend to stay together and don’t have offspring with people from other types of ethnicities. Experts say these mutations tend to stay within one group of individuals.

What distinguishes BRCA1 and BRCA2 genes is where they’re located in the chromosomes. There are also slight differences in terms of the types of cancers associated with the two genes.

The main difference in the two genes is that carriers of the BRCA1 gene mutation have a slightly increased risk of ovarian cancer compared to those with BRCA2. It is also known that carriers of BRCA2 genes have risks of different types of cancers, including pancreatic cancer and melanoma.

For ovarian cancer, women with a mutated BRCA1 gene have a 25 to 65 per cent lifetime risk of developing the disease. Those with a mutated BRCA2 gene have a 15 to 20 per cent chance of developing ovarian cancer.

For men, it is little different. For men with the BRCA2 mutation, there’s an increased risk of both prostate and breast cancers.

Who can ask for BRCA genetic testing?

There has to be a strong family history of cancer. The cancer must have occurred in young ages within the family and if you are a member of ethnic groups known to be affected then you would be eligible. If you don’t meet the criteria but still want to be tested then you can go south of the border and get yourself tested for about $3,000.

Early detection of breast cancer has dramatically changed the prognosis of the disease. We cannot say the same thing about ovarian cancer because we do not have any tests for early detection.

Each year, about 2400 Canadian women are diagnosed with ovarian cancer. Sadly, 1700 women with the disease die each year. In North America, ovarian cancer is the second most common gynecologic malignant disease and is the leading cause of death among women with gynecologic cancer.

More than 60 per cent of the women are in advanced stage when first diagnosed. Their five year survival rate is less than 30 per cent. Their prognosis is poor and they have very few treatment options. Some studies have reported higher survival rates of greater than 90 per cent in women with stage one disease. Only 25 per cent of the women are diagnosed early.

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