Putting on weight … if you’ve had localized prostate cancer


So even if we don’t want to think or talk about it, most of us are well aware that about 40 percent of all Americans are now obese. In other words, they have a body mass index (BMI) of 30 kg/m2 or higher.

A paper by Troeschel et al., just published in the Journal of Clinical Oncology, used data from the Cancer Prevention Study II Nutrition Cohort to look at associations between post-diagnosis body mass index (BMI) and weight change and prostate cancer–specific mortality (PCSM), cardiovascular disease–related mortality (CVDM), and all-cause mortality among survivors of non-metastatic prostate cancer.

In the Cancer Prevention Study II Nutrition Cohort, men with non-metastatic prostate cancer were all diagnosed between 1992 and 2013 and were followed for mortality through December 2016. The investigators collected the following data:

  • The patients’ current weight — which was self-reported on follow-up questionnaires every 2 years or so
  • The patients’ post-diagnosis BMI — which was obtained from the first questionnaire, completed 1 to < 6 years after diagnosis
  • Weight change — which was the difference in weight between the first and second post-diagnosis surveys
  • Deaths at > 4 years after initial follow-up (deaths at < 4 years after initial follow-up were excluded to reduce bias from reverse causation)

Here are some of the more important study findings:

  • Analyses of BMI and weight change included 8,330 and 6,942 participants, respectively.
  • Post-diagnosis BMI analyses included 3,855 deaths from all causes (PCSM, n = 500; CVDM, n = 1,155).
  • Hazard ratios (HRs) associated with post-diagnosis obesity (BMI ≥ 30 kg/m2) compared with healthy weight (BMI = 18.5 to < 25.0 kg/m2) were
    • 1.28 for PCSM
    • 1.24 for CVDM
    • 1.23 for all-cause mortality
  • Weight gain analyses included 2,973 deaths (PCSM, n = 375; CVDM, n = 881).
  • Post-diagnosis weight gain (> 5 percent of body weight), compared with stable weight (± < 3 percent of body weight), was associated with a higher risk of
    • PCSM (HR = 1.65)
    • All-cause mortality (HR = 1.27)

The authors conclude that their results

… suggest that among survivors of nonmetastatic prostate cancer with largely localized disease, postdiagnosis obesity is associated with higher CVDM and all-cause mortality, and possibly higher PCSM, and that postdiagnosis weight gain may be associated with a higher mortality as a result of all causes and prostate cancer.

An editorial commentary in the same issue of the journal (by Marshall and Joshu) digs into some of the details about the associations between obesity and prostate cancer. They point out that:

Among men with prostate cancer, obesity has been associated with a higher risk of recurrence after localized disease, higher risk of developing metastatic disease, and higher risk of prostate cancer–specific mortality. Observational evidence also suggests that even modest weight gain is associated with an increased risk of prostate cancer recurrence, fatal prostate cancer, and prostate cancer–specific mortality after a diagnosis of prostate cancer.

What’s the bottom line to all of this? That’s pretty straightforward:

  • Being overweight, and worse still being obese, is just not a good idea in the first place.
  • Being overweight or obese after a diagnosis of prostate cancer is probably an even worse idea.
  • As we all get older and take less exercise, it is all too easy to put on extra weight (and much harder to lose it)
  • You’d be wise to do something about it if you can!

Editorial comment: Your sitemaster (now aged 72 years) has been borderline diabetic for years. He has never been obese, but he now has to work hard to keep his BMI down below 25 kg/m2, and if he gets lazy about it (which he does every so often) his BMI can and does go back up to > 25 kg/m2 within a matter of weeks. On the other hand, he is — at least — doing his best to practice what he has preached above, even if he is less than perfect! As of today he is being “good”, and his BMI was 23.9 kg/m2 this morning! For most of us, once we are over about 50 years of age, maintaining a healthy BMI takes focus, determination, effort (as in regular and meaningful exercise), and an ability to restrain oneself from actually eating more of many things one would like to eat more of!

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