Sadly, it seems that everyone knows someone who has been affected by breast cancer. And many know someone diagnosed with advanced stage breast cancer or worse someone who has died from the disease. According to the National Cancer Institute, breast cancer is the leading cause of cancer death in women ages 15- 54. In honor of Breast Cancer awareness this month, I wanted to write a blog to review the risk factors for breast cancer along with reviewing the relatively new screening guidelines for non-high risk women ages 40-49.
In November of 2009, the guidelines as we know them (as Family Physicians) were changed by the United States Preventative Services Task Force (USPSTF). The change led to an uproar and then they were revised. USPSTF is just one of many organizations that put out guidelines about when to screen a woman for breast cancer. The US Preventative Services Task Force is an “independent panel of non-Federal experts in prevention and evidence-based medicine and is composed of primary care providers”. These experts “conduct scientific evidence reviews of a broad range of clinical preventive health care and develop recommendations for primary care clinicians”. What you should read into this is that they are unbiased.
I attended a lecture recently about breast cancer screening to ensure my knowledge was fresh and to see if I can add anything to my counseling sessions with my patients. I left the lecture even more confused about what to do. With a little time and more review, my thoughts on the matter are clearer. Here is the recommendation with more explanation to follow: The USPSTF recommends against screening mammography in women aged 40-49 years. The decision to start regular, biennial screening mammography before the age of 50 years should be an individual one and take into account patient context, including the patient’s values regarding specific benefits and harms. You can view all of their recommendations at: http://www.uspreventiveservicestaskforce.org/uspstf09/breastcancer/brcanrs.htm What does this mean? Or, one might say this recommendation is preposterous won’t it miss some women’s breast cancer? The USPSTF is not saying to stop screening all 40-49 year olds but to individualize the choice.
Before this change, in the US, we were recommending screening mammograms yearly starting at the age of 40 (in non high risk women) as well as asking women to consider a baseline mammogram between the ages of 35 and 40. Some organizations still uphold this prior recommendation: The American Cancer Society(ACS), The American College of Radiology(ACR), as well as the American College of Obstetricians and Gynecologists (ACOG). To take a look at some worldwide recommendations, the Australian Government’s Department of Health and Aging along with the United Kingdom’s National Health Service recommend screening mammograms starting at age 50. While in New Zealand, free mammograms are offered to all women ages 45-69. Here in the Gulf screening is recommended at the age of 50. For other country specific recommendations, you may look at the Geneva Foundation for Medical Education and Research website: http://www.gfmer.ch/Guidelines/Breast_diseases/Breast_cancer_screening.htm . In medicine, the pendulum swings in regard to recommendations. All of these current recommendations will continue to change as the evidence does.
Before we look at the benefits and harms, we will discuss who is at high risk? Age, ethnicity, family history, genetic predisposition, and estrogen exposure are the major risk factors for breast cancer in women. 1 in 69 women in their 40’s will be diagnosed with breast cancer. The incidence rises every decade to approximately 1 in 14 by the 70’s. About 1 in 8 women in the United States will develop invasive breast cancer over the course of her lifetime. Having one first-degree relative (mother, sister, or daughter) with breast cancer approximately doubles a woman’s risk. Only 5-10% of breast cancers are caused by inherited mutations of the BRCA1 or BRCA2 gene. But, the risk for breast cancer can be as great as 85% in one’s lifetime if you are found to carry a mutation. Having one of these genetic mutations also increases your risk for ovarian cancer. 1 in 40 of persons with Eastern European Jewish ancestry carry either a BRCA1 or BRCA2 gene mutation. Other factors which make a women high risk are: having a first-degree relative with a BRCA1 or BRCA2 gene mutation who have not had genetic testing themselves, having a lifetime risk of breast cancer 20 to 25%or greater, prior history of radiation therapy to the chest between the ages of 10 and 30 years, and having a genetic disease such as Li-Fraumeni syndrome, Cowden syndrome or Bannayan-Riley-Ruvalcaba syndrome, having first-degree relatives with one of these syndromes or having male relatives (1st, 2nd or 3rd degree) affected with breast cancer. All of these high risk women will need to be screened differently than is discussed in this article. Additional risk factors include: early age (<12 years old) at the start of your menstrual cycle (menarche), having your first baby after the age of 30, developing menopause at an older age (>55), drinking 2 or more alcoholic drinks per day, history of a benign breast biopsy, and history of atypical hyperplasia on breast biopsy. One study showed an increased risk of breast cancer with the use of oral contraceptives. Two other factors to consider are 1)that your paternal family history is just as important as your maternal and 2)the age of the breast cancers in affected relatives is important. The later could change your risk and impact when a physician would refer you for your first mammogram. Generally, a person would start having mammograms 10 years before the earliest diagnosis in their family including 1st, 2nd and 3rd degree relatives. Factors that are protective against breast cancer are exercise, breastfeeding (for at least 16 months), having a postmenopausal Body Mass Index (BMI) of less than 23, having 5 or more children, taking aspirin more than once a week, and having your ovaries surgically removed before the age of 35.
How do you find out what your breast cancer risk is? There are multiple breast risk assessment calculators that have been developed. One such calculator is called the “Gail Model” after its developer Dr Mitchell Gail at the National Cancer Institute. I say this cautiously as it was created for health care providers. If you calculate your risk, I would encourage you to discuss your results with your physician so you can make the best choice for you about screening mammography. Here is the link to a modified Gail model (it has fewer questions than the original calculator: http://www.cancer.gov/bcrisktool/. If you use the calculator, know that your calculated risk can change as two things change: 1) The evidence changes or 2) Your personal medical history changes. There are other risk calculators out there which will give you different results just to confuse things further. A dear friend of mine is a breast cancer genetics counselor. She likes to use the Claus Model and the Tyrer-Cuzick model “which consider 2nd and 3rd degree relatives which is also very important”. “The importance of meeting with a health care provider who has expertise in assessing risk cannot be emphasized enough.” I used the calculator on the National Cancer Institute’s website in 2009 and had a less than average risk of breast cancer then. Now, my risk is greater than average. My history has not changed, the evidence has. Here is an instructional video showing you how to calculate your own risk using the “ modified Gail Model” with a brief explanation of the results. Remember to go to full screen when you watch the video.
If you are not at high risk then what kinds of things do you need to discuss with your doctor before making the decision whether to have a mammogram before the age of 50? The harms vs. benefits! The potential benefits to screening can be reducing death from breast cancer and increasing survival. The potential harms are: radiation exposure, pain during the mammogram, anxiety over inconclusive results, false positives leading to additional testing and potentially unnecessary biopsies, and false negative results. For women ages 40-49, 3.2 deaths occurred per 1,000 women who were NOT screened with mammography. For women 40-49 who were screened 2.9 deaths occurred. What this means is that less than 1 of these women who had a mammogram will not die of breast cancer as compared to women who have never had a mammogram in this age range. Although, the ACR (American College of Radiology) noted that there is one case of invasive cancer found for every 556 mammograms performed in women in their 40’s. Not screening will therefore miss some cancers. You may say well then why not screen everyone? The goal is to reduce the harms while at the same time increasing the benefits which is quite a fine line. There are new technologies on the horizon that may soon be added to mammography which will make the benefits in mammography before 50 outweigh the risks. Digital tomosynthesis (only available for research purposes for now) takes multiple pictures (opposed to mammography which takes 1 picture in 2 directions: top to bottom and side to side) from many different angles creating a 3-D image of the breast using very little pressure. Researchers believe this will make cancers easier to see and more comfortable.
The amount of radiation from one mammogram is low and equivalent to 2 ½-3 months of your everyday environmental exposure. In regard to pain and anxiety, only you as the patient can judge how these two factors will be to you.. What kind of reaction do you think you may have to inconclusive or abnormal results? This may a bit hard to gauge when you are not in the situation. You may ask yourself: How well have you coped with medical diagnosis in the past or how to do you respond to stressors in general? I will have to say that I have had a small percentage of patients who were consumed with an inconclusive or abnormal mammogram result which required additional testing and sometimes biopsy. These women became almost non-functional in their day to day life until their workups were complete.
Let’s talk about how good a mammogram is at screening, and the false positives and negatives. Of all mammograms performed, 90% will come back without evidence of cancer. 10% will require further testing with additional views or ultrasound. With the additional testing, 85% will be normal and 15 % will require biopsy. However the total percentage of patients requiring biopsy is only 2%. Of all the biopsies performed, 80% will be normal and 20% cancerous. As you can see a mammogram can result in false positive results (around 10% in 40-49 year olds) and can lead to unnecessary biopsy. False negative results also occur at a rate of 8-10%. Despite not being 100% accurate, mammography has reduced the rate of death from breast cancer in the United States by 30% since 1990.
When I started this article, I wanted to completely uphold the new guidelines by the USPSTF as their standards have been the ones I routinely use. And to a certain extent I will. The new guidelines are not saying don’t offer mammograms to your 40-49 year olds but instead discuss whether a screening mammogram is right for their situation and allow the woman to make an informed decision. Here is where it makes it hard for me to fore go mammography before 50: as stated above, 1 invasive breast cancer is found for every 556 mammograms performed in the United States on women in their 40’s. Additionally if you start screening at age 50, you would sacrifice 33 years of life per 1,000 women screened that could have been saved if screening had started at 40. Lastly, doing biannual mammograms for women over 50 would miss 19-33 percent of cancers detected by yearly screening.
You may want to know what would I do? I know I should say it doesn’t matter what I would do as my risk is different than yours. However, I will share. Prior to the new guidelines, I started with a baseline mammogram at the age of 35, had another at the age of 38 and then another at the age of 41(not being able to have one at 40 as I was breastfeeding). I always planned on having yearly mammograms from the age of 40. After the guidelines were initially released, I had considered changing to biannual exams until the age of 50 and then going to yearly exams after 50. However, my risk changed. I now have a moderately increased risk for breast cancer based on the calculations of the “Gail Model”. My lifetime risk is 16.6% (as opposed to 12%). 15-20% lifetime risk puts you in this moderately increased risk category. While 20-25 lifetime risk makes you high risk. Therefore, the USPSTF guidelines no longer apply to me. I will have to admit, finding this out made me a bit “nutty” for a couple days. I used several other calculators (one giving me results as high as 29.2%). But then, I returned to reality and am going to continue screening yearly and not allow this increase in risk affect my life. In general, I favor yearly screening starting at the age of 40 for everyone (non high risk). Although each of you will have to decide what the best choice is for you. My hope is that I haven’t further confused you but allowed you to become more informed before your appointment with your primary care physician.