How do you want your steak prepared? The impact of meat consumption and preparation on prostate cancer

Abstract

Numerous epidemiological studies have suggested dietary factors may alter the risk of prostate cancer. Punnen and colleagues have conducted a case-control study focused on aggressive prostate cancer (N = 982), where not only details on meat consumption were collected, but also meat preparation was captured. A multivariate logistic regression model was used to assess the association between meat consumption, grilled meat consumption, doneness level, mutagens and aggressive prostate cancer. High consumption of processed meat, including ground beef, was associated with aggressive prostate cancer. Ground beef showed the strongest association (overall risk, OR = 2.30, 95% confidence interval, CI: 1.39–3.81; P-trend = 0.002). Well-done meat conferred a higher risk of aggressive prostate cancer. Interestingly, the consumption of rare or less cooked meat was not associated with an increased risk of prostate cancer. When the investigators evaluated the estimated meat mutagens produced by cooking at high temperatures, they identified an increased risk with MelQx and DiMelQx, OR = 1.69 95% CI: 1.08–2.64, P-trend = 0.02 and OR = 1.53 95% CI: 1.00–2.35, P-trend = 0.005, respectively.

In the United States, prostate cancer is the most common visceral cancer and the second most common cause of death.¹ The estimated lifetime risk of developing prostate cancer for Caucasians is 17.6% and 20.6% for African American males.¹ The fact that the risk of developing prostate cancer increases when men relocate from low to high-risk countries, suggests that an environmental factor may play a role in this disease. Numerous epidemiological studies have suggested dietary factors may alter the risk of prostate cancer.^2-5 High dietary fat has been shown to increase the risk, while diets consisting of rice, soybean products and vegetables have been suggested to decrease the risk.^6,7

Several studies have found an association between the consumption of meat and the development of prostate cancer.^8-10 Nonetheless, a meta-analysis by Alexander et.al. failed to confirm an independent positive association between red or processed meat intake and prostate cancer.¹¹ One explanation for the mixed results is that the key exposure is not just meat intake, but also how it is prepared.^12,13 Recent studies evaluating the doneness level or charred index of meat preparation have found an increased risk of prostate cancer when meat is cooked at high temperatures, such a grilling or pan-frying. Heterocyclic amines (HCA) and polycyclic aromatic hydrocarbons such as 2-amino-3, 8-dimethylimidazo (4,5-f)quinoxaline (MelQx), 2-amino-3, 8-dimethylimidazo(4,5-f)quinoxaline (DiMelQx), 2-amino-l-methyl-6-pheylimidozo(4,5-b)pyridine (PhIP) and benzo(a)pyrene (BaP), are found in well done or grilled meat.

Punnen and colleagues have conducted a case-control study focused on aggressive prostate cancer (n = 470 patients with prostate cancer and 512 controls), where not only details on meat consumption were collected, but also meat preparation was captured.¹⁴ A multivariate logistic regression model was used to assess the association between meat consumption, grilled meat consumption, doneness level, mutagens and aggressive prostate cancer.

The patients with prostate cancer and matched controls were recruited from the major medical institutions in Cleveland, Ohio. The cases were newly diagnosed men with histological confirmed disease, with any one of the following: Gleason score ≥ 7; tumor stage ≥ T2C; or a prostate specific antigen level greater than 10 ng/ml at diagnosis. Information regarding diet was collected using a validated semi-quantitative food frequency questionnaire (FFQ). The FFQ collected data on various types of foods consumed, including a range of meats and the frequency of consumption. A supplemental questionnaire asking about intake of grilled or barbequed meats and red meat doneness levels was added to the FFQ and completed by the study subjects at the same time. HCA and polycyclic aromatic hydrocarbon, including MelQx, DiMelQx, PhIP and BaP, consumption levels were estimated based on the red meat responses.¹⁴

High consumption of processed meat, including ground beef, was associated with aggressive prostate cancer. Ground beef showed the strongest association-overall risk OR = 2.30, 95% confidence interval CI: 1.39–3.81; P-trend = 0.002). Well-done meat conferred a higher risk of aggressive prostate cancer. Comparing those individuals that had high and low consumption of well/very well cooked ground beef to those that didn’t eat ground beef, the OR was 2.04 (95% CI: 1.41–2.96) and 1.51 (95% CI: 1.06–2.14), respectively. Interestingly, the consumption of rare or less cooked meat was not associated with an increased risk of prostate cancer. When the investigators evaluated the estimated meat mutagens produced by cooking at high temperatures, they identified an increased risk with MelQx and DiMelQx, OR = 1.69 95% CI: 1.08–2.64, P-trend = 0.02 and OR = 1.53 95% CI: 1.00–2.35, P-trend = 0.005, respectively.¹⁴

One question that is still unanswered deals with the pharmacogenetic of the mutagens. There are functional polymorphisms in both the enzymes that metabolize the heterocyclic amines and cellular transporters, which may alter the risk of developing prostate cancer. Genotyping should be added to this analysis.

The next time a patient asks you, “How can I reduce the risk that my son will develop prostate cancer?” these data may be useful. Encourage them to maintain a healthy weight and reduce the amount of meat in their diet, especially red meat and meats cooked at very high temperatures.¹⁵