Prostate Cancer Death Risk Higher In Obese Or Overweight Men

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Main Category: Prostate / Prostate Cancer
Also Included In: Obesity / Weight Loss / Fitness
Article Date: 13 Nov 2007 - 3:00 PDT

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A US study found that men who are obese or overweight when diagnosed with prostate cancer have a higher risk of death after treatment.

The study was conducted by Dr Jason Efstathiou of the Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts, and colleagues and was published online ahead of print on 12th November in the journal Cancer.

Efstathiou and co-authors found that men with a BMI of 25 or more at the time of diagnosis were nearly twice as likely to die from locally advanced prostate cancer as men with a lower BMI.

BMI stands for Body Mass Index, and is equal to the ratio of one's weight in kilos to one's height in metres, squared. For a man, a BMI under 25 is considered normal, 25 to under 30 is overweight, and 30 or more is obese.

Estimates from the American Cancer Society suggest that over 218,000 American men will be diagnosed with prostate cancer this year and the disease will kill 27,000. It is the second leading cause of cancer death in men, lung cancer being the first.

Obesity is a known risk factor for clinically aggressive prostate cancer, but there is less evidence about the impact of weight on survival after treatment, hence this study.

Treatments for prostate cancer include: surgical removal of the prostate gland, external beam radiation, and hormone treatment.

For the study, the researchers used data from a phase 3 trial involving 945 men with locally advanced prostated cancer who were enrolled between 1987 and 1992 and randomized to receive either radiation therapy and immediate hormone therapy (using goserelin, a GnRH agonist that stops the production of sex hormones), or radiation therapy followed by hormone therapy at recurrence.

They were able to get initial height and weight data for 788 of the patients and follow them for 8 years. This was the first large randomized prospective study with such a long follow up after treatment that looks at the link between BMI and death risk in men treated with radiation therapy and hormone (androgen deprivation) therapy for locally advanced prostate cancer.

Efstathiou and colleagues used regression analysis to find any statistically significant links between BMI and death risk from any cause, from prostate cancer-specific causes, and non-prostate cancer causes. Variables available, apart from BMI included: age, race, treatment arm, history of prostatectomy, nodes involved, Gleason score (a prognosis indicator), and clinical stage of the cancer.

The results showed that:

• Being overweight or obese at time of diagnosis was an independent risk factor for death from prostate cancer.
• Men with a BMI between 25 and under 30 (overweight) at the time of diagnosis were more than 1.5 times more likely to die from the cancer than men with normal BMI (i.e. lower than 25).
• Men with a BMI of 30 or over (obese) were 1.6 times more likely to die from the disease compared to men with normal BMI.
• After 5 years, men with BMI under 25 had a prostate cancer specific mortality rate of 6.5 per cent.
• This compared to 13.1 per cent for men with a BMI of 25 to under 30 (overweight) and 12.2 per cent for men with BMI of 30 or more (obese).
• BMI was not linked to non-prostate cancer mortality or mortality due to all causes.

Efstathiou and colleagues concluded that the study supported others reporting similar links between overweight or obesity and disease-related death rates:

"Greater baseline BMI is independently associated with higher PCSM [prostate cancer specific mortality] in men with locally advanced prostate cancer."

They called for further studies to find the mechanisms involved and to establish whether losing weight after being diagnosed affects outcomes and survival.

"Obesity and mortality in men with locally advanced prostate cancer."
Jason A. Efstathiou, Kyounghwa Bae, William U. Shipley, Gerald E. Hanks, Miljenko V. Pilepich, Howard M. Sandler, Matthew R. Smith.
Cancer Published Online: 12 Nov 2007
DOI: 10.1002/cncr.23093

Click here for Abstract.

Click here for more information about prostate cancer (American Cancer Society).

Written by: Catharine Paddock
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