Breast Cancer: Why I Prescribe Exercise

This is increasing evidence to support the use of physical activity as a part of the management of breast cancer. Potential benefits in cancer risk reduction, less fatigue with treatments such as chemotherapy or radiation therapy, improvements in the risk of at least 15 types of cancer and in cardiovascular disease, and better psychological well-being, and improved quality and length of life all come to mind. A lot of potential benefits. But today, I want to show you the results of a study published in the Journal of Clinical Oncology this week.

A condition known as metabolic syndrome is associated with an increased risk of heart disease and stroke, diabetes, and breast cancer recurrence among survivors of the disease. Researchers conducted a randomized clinical trial, examining the effects of a 16-week combined aerobic and resistance exercise intervention on metabolic syndrome, obesity, and blood markers among ethnically diverse, sedentary, overweight, or obese survivors of breast cancer.

Here’s what the researchers discovered at the 3 month follow-up mark:

Combined resistance and aerobic exercise effectively attenuated metabolic syndrome, obesity, and relevant biomarkers (such as insulin, insulin-like growth factor-1 (IGF-1), leptin, and adiponectin) in an ethnically diverse sample of sedentary, overweight, or obese survivors of breast cancer, as compared to usual care. Our findings suggest a targeted exercise prescription for improving metabolic syndrome in survivors of breast cancer and support the incorporation of supervised clinical exercise programs into breast cancer treatment and survivorship care plans.

I’m Dr. Michael Hunter, and I invite you to follow this blog by signing up below. Explore more here: Wellness! Thank you, and I hope you have a joy-filled day.


I am a radiation oncologist who serves patients in the Seattle area, and hold degrees from Harvard, Yale, and the University of Pennsylvania.

Breast Cancer: Do We Have a New Target?

Currently, chemotherapy is the only standard drug therapy for those with “triple negative” breast cancer. By triple negative, we mean that the cancer does not have estrogen receptors (it is ER negative), progesterone receptors (PR negative), or HER2 receptors (HER2 negative). Of the major groups of breast cancer, triple negative has the worst survival overall.

However, when we interrogate triple negative breast cancer cells with molecular assays, we find that there are distinct subjects of the entity. One subset expresses a receptor for “male hormone”; cancer cells that have these androgen receptors (AR-positive) have been shown to have a modest response to drugs that block androgen receptors. Examples of these AR-inhibitors include a abiaterone acetate and bicalutamide, drugs that we sometimes use to help manage prostate cancer in men.

Now researchers have conducted a study looking at enzalutamide, another androgen receptor inhibitor (that is sometimes used for prostate cancer that has spread to distant sites). How well did the drug work for patients with metastatic (spread to distant sites) androgen receptor positive, triple negative breast cancer? Certainly not extraordinary results, but at the 16 week mark the drug led to clinical benefit for 25 percent of patients; for the subgroup with androgen receptor over 10 percent, the clinical benefit was 33 percent. The most common severe side effect was treatment-related fatigue.

My take: The study did achieve its primary endpoint. Subsets of triple negative breast cancer may benefit from strategies targeting the androgen receptor in the future.

I am Dr. Michael Hunter, and I invite you to follow me (below) and to learn more here: Wellness!

My background? I have degrees from Harvard, Yale, and the University of Pennsylvania. I help folks with cancer in the Seattle area, serving as a radiation oncologist. Thank you for joining me today.


* above is the human androgen receptor ligand binding domain

Reference: J Clinical Oncology 2018 Jan 26; or try the web by clicking here: Targeting the Androgen Receptor in Triple-Negative Breast Cancer

Breast Cancer Genes: A New Consumer Test

Have you heard of 23andMe? In the USA, it is a leading consumer genetics and research company. I have used it to learn about my ancestry and genetic predispositions. But can the test help you spot weaknesses in your genes (maybe you have a mutation that puts you at higher risk for heart disease), providing you a change to make changes in your lifestyle to improve your risk? Well, we just got some big news from the US Food and Drug Administration (FDA) regarding 23andMe’s direct-to-consumer genetic test on cancer risk.

The test can use your saliva and check for genetic variants in the breast cancer genes 1 and 2 (BRCA1 and BRCA2). When such mutations are present, the risk of developing breast, ovarian, prostate, and colon cancer can increase dramatically. For example, the risk of breast cancer for a woman with a BRCA mutation may be up to 85 percent by the age of 70. While these mutations are most common among people of Ashkenazi Jewish descent, anyone could have a BRCA mutation. Wouldn’t it be nice if individuals knew if they had the gene, such that they could consider risk-reducing maneuvers (ranging from removing the breasts and ovaries, to incorporating MRI into regular breast screening)?

The FDA approval of this consumer test for evaluating your DNA for a BRCA mutation is a big deal. No prescription needed. You are empowered. And I’m Dr. Michael Hunter. I invite you to explore more of my blog here: Wellness! Please consider following me by signing up below. Thank you in advance.

Breast Radiation Therapy: Better Than Expected

A study recently published in the journal Cancer reports that the actual experiences among patients with breast cancer who undergo radiation therapy are at odds with their fears and misconceptions. We have much data regarding the effectiveness of radiation therapy at healing women keep their breast after a lumpectomy for localized breast cancer and to improve survival as well. Still, there is a paucity of information regarding the perspectives and experiences of out patients.

For the current study, researchers surveyed 502 patients with breast cancer who underwent radiation therapy as a part of curative management. They asked these patients about their fears regarding radiation therapy, and then checked in with them about their actual short- and long-term adverse events. About 65 percent of the patients responded to the survey, at a median follow-up of 31 months.

Nearly half (47 percent) of patients had heard frightening experiences about radiation therapy, although 68 percent stated that they had little or no knowledge about radiotherapy. Here’s the amazing thing: Only 2 percent of patients agreed that the stories they had heard proved true for them. Of the patients who had had breast-conserving surgery, fully 92 percent felt that if future patients were more knowledgeable about radiation therapy, they would be less scared of treatment.

I’m Dr. Michael Hunter, and I am a radiation oncologist in the Seattle area. I have degrees from Harvard, Yale, and the University of Pennsylvania. Please follow this blog by signing up below. And explore more here at my other blog site: Wellness! Thank you.

Nighttime Light Exposure: Does It Increase Your Risk of Breast Cancer?

Women who live in areas with higher levels of outdoor light at night may be at higher risk for breast cancer than those living in areas with lower levels, according to a large long-term study from the Harvard T.H. Chan School of Public Health. The link was stronger among women who worked night shifts.


Background: Previous studies have suggested that exposure to light at night may lead to decreased levels of the hormone melatonin, which in turn can disrupt circadian rhythms – out internal “clocks” that regulate sleepiness and alertness. As a result, your risk of breast cancer may increase.

The Study: In the most comprehensive study to date (investigating possible links between  outdoor light at night and breast cancer, researchers examined data from nearly 110,000 women enrolled in the Nurses’ Health Study II from 1989-2013. The researchers linked data from satellite images of earth taken at nighttime to residential addresses for each study participant, and also considered the influence of night shift work. The study also factored in detailed information on a variety of health and socioeconomic factors among participants.

Results: Women exposed to the highest levels of outdoor light at night — those in the top fifth — had an estimated 1.14-times increased risk of breast cancer during the study period, as compared with women in the bottom fifth of exposure. As levels of outdoor light at night increased, so did breast cancer rates. The association between outdoor light at night and breast cancer was found only among women who were premenopausal and those who were current or past smokers. In addition, the link was stronger among women who worked night shifts, suggesting that exposure to light at night and night shift work contribute jointly to breast cancer risk, possibly through mechanisms involving circadian disruption.


My Take: While provocative and consistent with historic studies, there are many potential variables for which the investigators did not control. Still, while we need confirmatory studies, this may be a caution regarding night exposure. For my patients, this typically means limiting blue light exposure in the hour before bedtime. Watch out for those computer screens, cell phones, and televisions! I’m Dr. Michael Hunter.


The small print: The material presented herein is informational only, and is not designed to provide specific guidance for an individual. Please check with a valued health care provider with any questions or concerns. As for me, I am a Harvard- , Yale- and UPenn-educated radiation oncologist, and I practice in the Seattle, WA (USA) area. I feel genuinely privileged to be able to share with you. If you enjoyed today’s offering, please consider clicking the follow button at the bottom of this page.

And, one more thing: NEW free apps for Android and iOS (Apple): In apps, search My Breast Cancer by Michael Hunter.


Reference: Peter James, Kimberly A. Bertrand, Jaime E. Hart, Eva Schernhammer, Rulla M. Tamimi, Francine Laden. Outdoor Light at Night and Breast Cancer Incidence in the Nurses’ Health Study II. Environmental Health Perspectives, 2017 DOI: 10.1289/EHP935


Poor adolescent diet associated with premenopausal breast cancer

“During adolescence and early adulthood, when the mammary gland is rapidly developing and is therefore particularly susceptible to lifestyle factors, it is important to consume a diet rich in vegetables, fruit, whole grains, nuts, seeds, and legumes and to avoid soda consumption and a high intake of sugar, refined carbohydrates, and red and processed meats.”

– lead author Karin B. Michels, ScD, PhD, professor and chair of the Department of Epidemiology at the UCLA Fielding School of Public Health, Los Angeles

Key points: Women who consumed a diet associated with chronic inflammation  as adolescents or young adults appear to have a higher risk of developing premenopausal breast cancer, as compared with those who had a diet not linked to inflammation.

Background: Researchers used data from 45,204 women in the Nurses’ Health Study II who had completed a food frequency questionnaire in 1998, when they were ages 33 to 52, about their diet during high School. The investigators then assed adult diet by first using a food frequency questionnaire in 1991, when participants were ages 27 to 44, and then every 4 years thereafter. They gave each woman’s diet an inflammatory score using a previously method that links diet with inflammatory markers in the blood.

During 22 years of follow-up, 870 of the women who completed the high school food frequency questionnaire were diagnosed with premenopausal breast cancer and 490 were diagnosed with postmenopausal breast cancer. When women were divided into five groups based on the inflammatory score of their adolescent diet, those in the highest score group had a 35 percent higher risk for premenopausal breast cancer relative to those in the lowest score group. When the same analysis was done based on early adulthood diet, those in the highest inflammatory score group had a 41 percent higher risk for premenopausal breast cancer relative to those in the lowest score group.

I’m Michael Hunter, the Breast Cancer Doctor.

Should doctors prescribe exercise?

“Although the data vary by different cancer types, there is a consistent trend suggesting that moderate daily exercise has a beneficial effect on preventing certain cancers. If you are a reasonably healthy adult, your should exercise regularly.” 

Let’s look at the relationship of exercise and selected cancers. The American Society of Clinical Oncology (ASCO) has done a nice job of summarizing:

Breast Cancer

While the amount of risk reduction varies among studies (20-80%), most suggest that 30 to 60 minutes of moderate to high-intensity exercise per day lowers breast cancer risk. Women who are physically active throughout their life appear to benefit the most, but those who increase physical activity after menopause also fare better than inactive women.1

Colon Cancer

Research suggests that people who increase their physical activity can lower the chance of developing colon cancer by 30 to 40% relative to sedentary adults.1,2 A decrease in colon cancer risk can be achieved regardless of body mass index (BMI) and people who are most active benefit the most. There is insufficient evidence of a protective effect of physical activity on the risk of rectal cancer (a protective effect was seen in some case-control studies, but not in cohort studies).3

Endometrial, Lung and Ovarian Cancer

A handful of studies have suggested that women who are physically active have a 20-40% reduced risk of endometrial cancer compared to those who don’t exercise.1 Higher levels of physical activity seem to also protect against lung cancer (up to 20% reduction in risk), particularly among men.1Although less consistent, research suggests that physical activity possibly reduces the risk of ovarian and prostate cancer.

What about Other Cancers?

While observational data on the benefits of exercise for prevention of the types of cancers listed above are fairly consistent, evidence of the effects of exercise on prevention of any other type of cancer either is either insufficient or inconsistent.2,4

Prostate Cancer

Prostate cancer is one disease in which the data are not consistent, however prostate cancer is a heterogeneous disease and risk factor associations for total non-aggressive disease are different from aggressive / lethal disease. Most population based studies show similar findings, with little effect of exercise on overall incidence of prostate cancer but lower risk of aggressive prostate cancers for those with the highest levels of VIGOROUS activity (rather than any type of activity). In the Health Professionals Follow-up Study men 65 years or older who engaged in vigorous physical activity, such as running, jogging, biking, swimming or tennis at least three hours per week  had a 67% lower risk of advanced prostate cancer and 74% lower risk of fatal prostate cancer.5

Conflicting data for other malignancies

For example, one recent study found no association between physical activity and risk of developing gastric, rectal, pancreatic, bladder, testicular, kidney and hematological cancers.4 In contrast, a pooled analysis of data from prospective trials with 1.4 million participants found that physical activity was linked to lower risk of 13 cancers: esophageal, lung, kidney, gastric, endometrial, myeloid leukemia, myeloma, colon, head and neck, rectal, bladder, and breast.6Interestingly, leisure-time physical activity was associated with a higher risk of melanoma (presumably due to time spent outdoors) and prostate cancer, although it is not clear from these data whether that association was with nonaggressive or aggressive prostate cancer.

While we wait for confirmation and clarity on the role of exercise in preventing all the 200+ types of cancer – should doctors prescribe exercise? The answer is simple: yes, because evidence of the protective role of exercise is already strong for some of the most common cancers.


  1. Lee I, Oguma Y. Physical activity. In: Schottenfeld D, Fraumeni JF, editors. Cancer Epidemiology and Prevention. 3rd ed. New York: Oxford University Press, 2006.
  2. Slattery, ML. Physical activity and colorectal cancer. Sports Medicine 2004; 34(4): 239–252.
  3. Pham NM, et al. Physical activity and colorectal cancer risk: an evaluation based on a systematic review of epidemiologic evidence among the Japanese population. Jpn J Clin Oncol. 2012 Jan;42(1):2-13.
  4. Friedenreich CM, Neilson HK, Lynch BM. Eur J Cancer. State of the epidemiological evidence on physical activity and cancer prevention. 2010 Sep;46(14):2593-604.
  5. Giovannucci E, Liu Y, Leitzmann MF, et al. A prospective study of physical activity and incident and fatal prostate cancer. Arch Intern Med. 2005; 165(9):1005-1010.
  6. Moore SC, Lee IM, Weiderpass E, et al. Association of Leisure-Time Physical Activity With Risk of 26 Types of Cancer in 1.44 Million Adults. JAMA Intern Med. 2016 Jun 1;176(6):816-25.

I’m Dr. Michael Hunter. Of course, the disclaimer: Do not begin an exercise program without input from an appropriate medical professional. Many can simply start with a brisk walk for 30 minutes daily, 5 days per week. Have a wonderful day!