How to cut your overall risk for all cancer by 51 percent, BUT …

There has been significant media coverage of a recent article in the journal Circulation. The article reports that individuals enrolled in the Atherosclerosis Risk in Communities (ARIC) study were able to cut their overall risk for cancer by 51 percent. However, in the specific case of prostate cancer, risk reduction appears not to be quite so simple as it is for other common cancers like breast, lung, and colorectal cancers.

Rasmussen-Torvik et al. carried out a detailed re-analysis of data from 13,253 individuals who had participated in the ARIC study. That study was originally designed to explore whether adherence to ideal levels of the seven cardiovascular health metrics specified by the American Heart Association (AHA) actually cut risk for cardiovascular mortality. It did … by 55 percent, and participants only needed to meet three or four of the seven specified goals as opposed to just two over 11 years of follow-up. In this new re-analysis, the authors wanted to know if adherence to ideal levels of the same seven cardiovascular health metrics reduced risk for cancer. Another detailed discussion of the study and its results (along with a video commentary) can be found on the MedPageToday web site.

So first and foremost, what are the seven cardiovascular health metrics specified by the AHA? They are:

  • Never having smoked at all or having stopped smoking at least 12 months previously
  • Regular physical activity (i.e., at least 75 min/week of vigorous physical activity or 150 min/week of moderate or moderate + vigorous activity)
  • Avoiding obesity (i.e., having a body mass index or BMI < 25 kg/m2)
  • Having a well balanced dietary intake (i.e., having four of five components of a healthy diet score)
  • Maintaining an untreated total cholesterol of < 200 mg/dl
  • Having an untreated blood pressure of < 120 mm Hg systolic and 80 mm Hg diastolic
  • Having an untreated fasting serum glucose level of < 100 mg/dl

The AHA’s MyLifeCheck™ web site already allows any patient to assess his or her risk for heart disease based on these seven cardiovascular health metrics.

Rasmussen-Torvik et al. had access to all relevant data on the baseline characteristics of the 13,000+ participants, and none of the participants had cancer of any type at the time their entry into the study. Based on the baseline data, they were able to classify all of the study participants according to the seven AHA cardiovascular health metrics. They were also able to obtain cancer incidence data on the patients (excluding only non-malignant forms of skin cancer) between 1987 and 2006 through the use of cancer registries and hospital surveillance programs.

Here are the major study findings:

  • The average (mean) age of study participants at baseline was 54.
  • The participants included slightly more women than men.
  • There were 2,880 incident cancer cases among the 13,253 participants over 17 to 19 years of follow-up.
  • There was a significant, graded, inverse association between the number of ideal cardiovascular health metrics at baseline and cancer incidence (p-trend < 0.0001).
  • Just 2.7 percent of the participants met goals for six or seven of the ideal health metrics, and only 16/13,253 participants (0.1 percent) met all seven goals.
  • The participants who met six or seven of the goals had a 51 percent lower risk of incident cancer than those meeting none of the goals for ideal health metrics.
  • If smoking was removed from the sum of ideal health metrics, the association was attenuated and participants who met goals for five or six of the remaining health metrics had a 25 percent lower risk of incident cancer than those meeting none of the goals ideal health metrics (p-trend = 0.03).

and now here’s the BUT ….

Rasmussen-Torvik et al were “surprised” to note that

  • Prostate cancer incidence actually increased (modestly) with an increasing number of ideal health metrics.
  • When the smoking goal was eliminated from the score of ideal health metrics, the association of the score with higher incidence of postate cancer was no longer observed (p-trend = 0.40).

The authors point out that a previous cohort study, which included > 250,000 men, showed that smoking was actually associated with a reduced incidence of non-advanced prostate cancer, but with an increased risk for fatal prostate cancer.

The idea that good cardiovascular health is associated with lower risk for cancer is by no means a new one. However, the data generated by Rasmussen-Torvik and her colleagues appear to suggest that this may not be the case specifically for prostate cancer. Dr. Rasmussen-Torvik was kind enough to spend some time talking to me about this by phone. While she was very clear that, in the current study, they simply did not have data available to be able to clarify this unexpected result, we both agreed that the key message here for men of 40 to 60 years of age is that good adherence to the AHA’s seven cardiovascular health metrics will cut your risk for death from cardiovascular disorders and reduce your risk of a diagnosis with any form of malignant cancer. This is by no means a bad thing.

It is also clear that better data on the AHA’s seven cardiovascular health metrics will be needed to explore, with greater rigor, any association between lifestyle, risk for prostate cancer (by stage and grade), and prostate cancer-specific mortality.

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