Examining screening mammography participation among women aged 40 to 74

Karena D. Volesky; Paul J. Villeneuve

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Please do not forget the lack of physical activity
Martin Hofmeister

Published on: 17 July 2017
RE: Examining screening mammography participation among women aged 40 to 74
Alan Katz

Published on: 22 June 2017

Published on: (17 July 2017)

Please do not forget the lack of physical activity
Martin Hofmeister, Dr., Consumer Centre of the German Federal State of Bavaria, Department Food and Nutrition, Germany
Dear Editor,

I congratulate Ms. Volesky and Dr. Villeneuve for their very interesting article “Examining screening mammography participation among women aged 40 to 74” in the June 2017 issue of the Canadian Family Physician [1]. The authors wrote: “Modifiable factors associated with breast cancer include alcohol consumption, smoking, hormone replacement therapy, and postmenopausal obesity.” These factors mentioned were included, among others, in the data analysis. There is one important modifiable lifestyle aspect worth mentioning.

Moderate levels of physical activity can reduce breast cancer risk, which has been observed 30 years ago [2-4]. Today, convincing evidence exists for this association. Several recent meta-analyzes show that physically active women have a 12-25% lower risk of breast cancer compared to the least active women [5-8]. This risk reduction also applies to household physical activity (relative risk 0.78 (95% confidence interval (CI) 0.69-0.89)) [9]. There is generally a clear dose-response relationship between physical activity and breast cancer risk [7]. In the above citation, the authors refer to references (e.g. Colditz et al. CA Cancer J Clin. 2014;64(3):186-94), which also call "lack of physical activity" as one of the established modifiable causes of breast cancer.

The authors have included the study by Maxwell et al. in their references, but unfortunately it was not mentioned that this Canadian study examined infreq...
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Dear Editor,

I congratulate Ms. Volesky and Dr. Villeneuve for their very interesting article “Examining screening mammography participation among women aged 40 to 74” in the June 2017 issue of the Canadian Family Physician [1]. The authors wrote: “Modifiable factors associated with breast cancer include alcohol consumption, smoking, hormone replacement therapy, and postmenopausal obesity.” These factors mentioned were included, among others, in the data analysis. There is one important modifiable lifestyle aspect worth mentioning.

Moderate levels of physical activity can reduce breast cancer risk, which has been observed 30 years ago [2-4]. Today, convincing evidence exists for this association. Several recent meta-analyzes show that physically active women have a 12-25% lower risk of breast cancer compared to the least active women [5-8]. This risk reduction also applies to household physical activity (relative risk 0.78 (95% confidence interval (CI) 0.69-0.89)) [9]. There is generally a clear dose-response relationship between physical activity and breast cancer risk [7]. In the above citation, the authors refer to references (e.g. Colditz et al. CA Cancer J Clin. 2014;64(3):186-94), which also call "lack of physical activity" as one of the established modifiable causes of breast cancer.

The authors have included the study by Maxwell et al. in their references, but unfortunately it was not mentioned that this Canadian study examined infrequent physical activity as a significant predictor of never having had a mammogram in women aged 50-69. The adjusted odds ratio was 1.54 (95% CI 1.19-1.98) compared with regular or occasional physical activity [10]. As a clearly demonstrated modifiable risk factor for breast cancer, the physical activity level should be taken into account in planned further analysis of the data regarding screening mammography participation.

Sincerely,

Dr. Martin Hofmeister, Consumer Centre of the German Federal State of Bavaria, Department Food and Nutrition, Germany

References

1. Volesky KD, Villeneuve PJ. Examining screening mammography participation among women aged 40 to 74. Can Fam Physician 2017;63(6):e300-e309.

2. Frisch RE, Wyshak G, Albright NL, Albright TE, Schiff I, Jones KP, et al. Lower prevalence of breast cancer and cancers of the reproductive system among former college athletes compared to non-athletes. Br J Cancer 1985;52(6):885-91.

3. Ross RK, Bernstein L, Garabrant D, Henderson BE. Avoidable nondietary risk factors for cancer. Am Fam Physician 1988;38(2):153-60.

4. Albanes D, Blair A, Taylor PR. Physical activity and risk of cancer in the NHANES I population. Am J Public Health 1989;79(6):744-50.

5. Lynch BM, Neilson HK, Friedenreich CM. Physical activity and breast cancer prevention. Recent Results Cancer Res 2011;186:13-42.

6. Wu Y, Zhang D, Kang S. Physical activity and risk of breast cancer: a meta-analysis of prospective studies. Breast Cancer Res Treat 2013;137(3):869-82.

7. Kyu HH, Bachman VF, Alexander LT, Mumford JE, Afshin A, Estep K, et al. Physical activity and risk of breast cancer, colon cancer, diabetes, ischemic heart disease, and ischemic stroke events: systematic review and dose-response meta-analysis for the Global Burden of Disease Study 2013. BMJ 2016;354:i3857.

8. Neilson HK, Farris MS, Stone CR, Vaska MM, Brenner DR, Friedenreich CM. Moderate-vigorous recreational physical activity and breast cancer risk, stratified by menopause status: a systematic review and meta-analysis. Menopause 2017;24(3):322-44.

9. Shi Y, Li T, Wang Y, Zhou L, Qin Q, Yin J, et al. Household physical activity and cancer risk: a systematic review and dose-response meta-analysis of epidemiological studies. Sci Rep 2015;5:14901.

10. Maxwell CJ, Bancej CM, Snider J. Predictors of mammography use among Canadian women aged 50-69: findings from the 1996/97 National Population Health Survey. CMAJ 2001;164(3):329-34.
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Competing Interests: None declared.
Published on: (22 June 2017)

RE: Examining screening mammography participation among women aged 40 to 74
Alan Katz, Family Physician, Department of Family Medicine, University of Manitoba
The authors correctly point out some of the limitations of this study related to the use of self report data, however, breast screening programs in Canada are offered in every jurisdiction as public health programs. Indeed objective data are collected by each of these programs.

Of greater concern is the failure of the authors to analyze the findings adequately by age group. They fail to differentiate between women less than 50 where screening is not recommended in Canada and those in the older age groups. In addition they misinterpret their own findings: "...factors related to health care use exerted a stronger effect. Having a regular doctor, a physical checkup in the past year, and a Pap test in the past 3 years were strongly related to whether women aged 40 to 74 participated in screening mammography in 2012." This language suggests a causal relationship between the associated factors and screening mammography. In particular "exerting a stronger effect" is clearly an unfounded statement. The study does not support this causal relationship. Indeed with the current state of knowledge of mammography screening it would not be surprising if rates of screening were lower in women who had meaningful discussions with their family doctors(1).

Reference

1.Katz A. Family doctors should engage with patients about mammography. Eur J Cancer Care. 2017;26:e12701. https://doi.org/10.1111/ecc.12701...
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The authors correctly point out some of the limitations of this study related to the use of self report data, however, breast screening programs in Canada are offered in every jurisdiction as public health programs. Indeed objective data are collected by each of these programs.

Of greater concern is the failure of the authors to analyze the findings adequately by age group. They fail to differentiate between women less than 50 where screening is not recommended in Canada and those in the older age groups. In addition they misinterpret their own findings: "...factors related to health care use exerted a stronger effect. Having a regular doctor, a physical checkup in the past year, and a Pap test in the past 3 years were strongly related to whether women aged 40 to 74 participated in screening mammography in 2012." This language suggests a causal relationship between the associated factors and screening mammography. In particular "exerting a stronger effect" is clearly an unfounded statement. The study does not support this causal relationship. Indeed with the current state of knowledge of mammography screening it would not be surprising if rates of screening were lower in women who had meaningful discussions with their family doctors(1).

Reference

1.Katz A. Family doctors should engage with patients about mammography. Eur J Cancer Care. 2017;26:e12701. https://doi.org/10.1111/ecc.12701
Show Less

Competing Interests: None declared.