Should doctors prescribe exercise?

young woman running city park

“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.

References

  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.
  7. http://www.asco.org/about-asco/press-center/asco-resources-media/cancer-perspectives/should-cancer-doctors-prescribe?et_cid=38723632&et_rid=463715101&linkid=Read+more

 

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!

Hormone Replacement Therapy Increases Ovarian Cancer Risk

What You Need to Know: Taking hormone replacement therapy (HRT) for menopause, even for just a few years, is associated with a small increased risk of developing the two most common types of ovarian cancer, according to a detailed re-analysis of all the available evidence.

The Evidence: The findings from a meta-analysis (a study of a collection of studies) of 52 epidemiological studies, involving a total of 21488 women with ovarian cancer, almost all from North America, Europe and Australia, indicate that women who use HRT for just a few years are about 40% more likely to develop ovarian cancer than women who have never taken HRT.

“For women who take HRT for 5 years from around age 50, there will be about one extra ovarian cancer for every 1000 users and one extra ovarian cancer death for every 1700 users”, explains study co-author Professor Sir Richard Peto from the University of Oxford in the UK.

The effect of HRT on the risk of developing ovarian cancer was the same for the two main types of HRT (preparations containing oestrogen only, or oestrogen together with a progestagen). Likewise, the proportional increase in risk was not materially affected by the age at which HRT began, body size, past use of oral contraceptives, hysterectomy, alcohol use, tobacco use, or family history of breast or ovarian cancer.

There are, however, four main types of ovarian cancer, and an increase in risk was seen only for the two most common types (serous and endometrioid ovarian cancers), and not for the two less common types (mucinous and clear cell ovarian cancers).

My Take: While hormone replacement therapy can provide benefits for selected individuals, this study reminds us to be prudent: If you must use HRT (for example, for hot flashes not controlled by acupuncture, exercise, and attention to triggers such as heat, caffeine, alcohol, stress, and spicy foods), use the lowest dose of HRT that you can, for as short a duration as possible. HRT can also increase the risks of breast cancer and cardiovascular events (but may lower your risk of colon cancer, and help with hot flashes (among other symptoms of menopause). I’m Dr. Michael Hunter.

References: 

  1. Collaborative Group on Epidemiological Studies of Ovarian Cancer. Menopausal hormone use and ovarian cancer risk: individual participant meta-analysis of 52 epidemiological studies. The Lancet, 2015 DOI: 10.1016/S0140-6736(14)61687-1
  2. The Lancet. “Short-term use of hormone replacement therapy associated with increased ovarian cancer risk.” ScienceDaily. ScienceDaily, 12 February 2015. <www.sciencedaily.com/releases/2015/02/150212211945.htm>.

Skip The Stirrups: Doctors Rethink Yearly Pelvic Exams

What You Need to Know: The American College of Physicians said Monday that it strongly recommends against annual pelvic exams for healthy, low-risk women. In fact, the intrusive exams may do more harm than good for women who aren’t pregnant or don’t have signs of problems, a group of doctors wrote in the Annals of Internal Medicine. So, No More Pelvic Exams? Not so fast. The recommendation to omit them for women at healthy, low risk women is not shared by the American College of Obstetricians and Gynecologists. My Take: There is no evidence to support or refute the annual pelvic examination for the asymptomatic, low-risk patient. For now, you should discuss (with your healthcare providers) whether a full exam is necessary. But don’t forget the PAP smear, as it saves lives. There’s no evidence that the bimanual exam cuts your risk of dying from ovarian cancer, however, so your doctor may want to skin the manual exam. 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. Available now: Understand Colon Cancer in 60 Minutes; Understand Brain Glioma in 60 Minutes. Both can be found at the Apple Ibooks store. Coming Soon for iPad: Understand Breast Cancer in 60 Minutes; Understand Colon Cancer in 60 Minute; Understand Colon Cancer in 60 Minutes; Understand Brain Glioma in 60 Minutes. Thank you. Reference: http://www.npr.org/blogs/health/2014/06/30/326703530/skip-the-stirrups-doctors-rethink-yearly-pelvic-exams?utm_source=facebook.com&utm_medium=social&utm_campaign=npr&utm_term=nprnews&utm_content=20140701

Dogs Sniffing Out Cancer: Really?

Golden Retriever
Golden Retriever (Photo credit: rkleine)

Well, yes. Really. Investigators at the University of Pennsylvania (Philadelphia, USA) have joined with Penn Vet Working Dog Center to try to sniff out early ovarian cancer, a potentially silent killer that is often diagnosed too late.

Background: Ovarian cancer will kill more than 14,000 women in the USA this year (and 22,000 new cases will be found). We don’t have a great screening tool for ovarian cancer, so researchers are hoping the dogs and their keen sense of smell can lead them to one.

Cancer cells have a detectable biomarker. So engineering students at Penn designed a large wheel with paint cans on the end of each spoke. Only one of the cans has cancer tissue in it. If the dog correctly identifies it, it is rewarded with time with a treasured toy.

The research is an interdisciplinary effort between the Penn Vet Working Dog Center and the University of Pennsylvania. There are 3 parallel studies: 1) the biologic one with the dogs; 2) an organic chemistry effort to create an artificial nose; and 3) nanotechnology to develop a computerized screening instrument.

My take: Intriguing. The researchers build on 2010 work from Sweden, where pet giant schnauzers showed a sensitivity of 100% (if cancer was there, the dogs always found it), and specificity of 95% (   ). Dogs with long noses (think hunting dogs such as Labradors, golden retrievers and springer spaniels) have the largest surface area for smell receptors. 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.

Available now: Understand Colon Cancer in 60 Minutes; Understand Brain Glioma in 60 Minutes. Both can be found at the Apple Ibooks store. Coming Soon for iPad:  Understand Breast Cancer in 60 Minutes; Understand Colon Cancer in 60 Minuteable now: Understand Colon Cancer in 60 Minutes; Understand Brain Glioma in 60 Minutes. Thank you.

Reference: BC News (USA) 09 August 2013

What are BRCA mutations?

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Angelina Jolie has put personalized medicine in the spotlight. Her mother died at age 56 following a 10 year battle with cancer. Jolie recently published a powerful New York Times op ed piece revealing her personal journey after testing positive for a BRCA mutation and her subsequent decision to have risk-reducing removal of her breasts and ovaries. In today’s blog, we turn to the basics of BRCA mutations. What are they, and what are the risks they pose?

BRCA stands for BReast CAncer susceptibility gene. We have BRCA1 and BRCA2, initially discovered by Dr. Claire King at the University of Washington, Seattle. You and I have BRCA genes; in fact we all do. They are tumor suppressor genes that help to keep your cells’ genetic material stable and to prevent cells from growing uncontrollably.

Among women, BRCA mutations (changes) have been associated with a marked increase in the risk of breast and ovarian cancer, often at an early age. On average, the risk of breast cancer increases from 12% (for the average woman in the USA) to about 60% or more among those with a BRCA mutation. The lifetime risk for ovarian cancer increases too, from about 1.4% in the general population to as much as 40%.

Unfortunately, there is more. BRCA1 mutations also increase the risk of cervix, uterus, colon, and pancreas cancer. And BRCA2 mutations also increase the risk of stomach, gallbladder, pancreas, and bile duct tumors as well as melanoma. Among men, BRCA mutations can increase the risk of male breast cancer, with BRCA1 mutations also associated with a higher risk of testicular cancer, and BRCA2 mutations increasing the risk for prostate cancer.

Genetic counseling can be remarkably informative. We will discuss who should consider BRCA testing in a future blog. Thank you. I’m Dr. Michael Hunter.

The small print: Anything stated here is for general use only, and should not be construed as medical advice for an individual. Please check with your health care provider with any questions or concerns.