'Fat Hormone' Tied to Higher Colon Cancer Risk in Obese Men

Obesity seems to increase the likelihood for developing precancerous growths called colorectal polyps, according to new research that offers fresh insight into colon cancer risk. Specifically, the study links polyp risk to several key characteristics of obesity, including having elevated levels of the fat hormone leptin, having a higher body mass index (BMI) and having a larger waistline. BMI is a measurement of body fat taking height and weight into account. However, investigators stressed that the current findings are not, as yet, definitive, and should not lead to any immediate revisions of current colorectal screening recommendations. Co-author said the study "cannot assume any cause, only association." In order to change the recommendations, which right now advise men to get screened starting at the age of 50, we'd have to find out if obese men are more likely to develop these polyps at an earlier age than their lean counterparts," she explained. "But we can't yet say that," she said. "For the moment, all we can say for sure is that obese men in this particular population were more likely to have polyps. We will need larger studies following a more generalized population over time to learn about timing." To explore a potential link between obesity and colon cancer risk, between mid-2009 and early 2011 the authors focused on 126 seemingly healthy men aged 48 to 65, all of whom were Michigan residents. All the men underwent colonoscopies. In addition, the team noted BMI scores, waist measurements and leptin levels for all participants. Roughly four in 10 of the men were found to be obese (with a BMI of 30 and up), with 78 percent falling into the category of either obese or overweight. And when focusing on the overweight/obese group, the team found that 30 percent had more than one polyp. After cross-referencing overall results, the investigators determined that men who were obese faced a 6.5 times greater risk for having three or more colorectal polyps than those who were lean (with a BMI under 25). Obese men were also found to face an almost eight times greater risk than lean men for having at least one polyp, as opposed to none. What's more, polyp risk seemed to rise incrementally with body fat status. Specifically, polyp risk was seen to rise by a factor of nearly three when lean men were compared to overweight men. And risk went up again by the same amount when comparing overweight men to obese men. Importantly, the team also found that having higher levels of the fat hormone leptin was similarly associated with having a higher risk for developing polyps. Co-author said that her previous work has already uncovered evidence for how the obesity-colon cancer connection might function. "We found that precancer cells, find in a polyp, are very sensitive to leptin," she said. "And leptin increases with fat cell size and number. So in a laboratory setting and with animals we've seen that leptin makes these early cancer cells grow," she explained. "So while we can't yet add obesity to the risk profile for colon cancer, we do think we understand the mechanism behind this," she noted. "And if this is confirmed in a larger population it could lead to a change in screening protocols."

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Higher HIV Infection Rates Seen in Mental Health Patients: Study

Americans seeking treatment for mental health disorders may be four to 16 times more likely to be infected with HIV than those in the general population, a new study reveals. The findings emphasize the need to provide testing for HIV -- the virus that causes AIDS -- in mental health care facilities, the researchers said. The study authors provided HIV testing to more than 1,000 people in Philadelphia and Baltimore who sought treatment for mental health problems such as depression, psychosis and substance abuse from January 2009 to August 2011. About 4.8 percent of these patients were infected with HIV. That's 16 times higher than the rate of 0.3 percent in the overall U.S. population, and about four times higher than the rates of 1.4 percent in Philadelphia and 1.3 percent in Baltimore. Both cities are HIV epicenters, the researchers noted. Thirteen of the 51 mental health patients found to have HIV did not know they were infected, according to the study. The findings showed that HIV infection was more common among people with more severe symptoms of mental illness and among groups of people most likely to be infected in the general population, including blacks, gay or bisexual men, and those with hepatitis C, which often indicates past injection drug use. "These findings paint a recent picture of HIV infection rates in the community, and reinforce how important it is to identify patients and get them into appropriate infectious disease care in a timely manner while being treated for mental illness," study lead author said. "With such a high-risk group, it's imperative to be routinely testing patients to improve care and reduce transmissions to others. Historically, though, HIV testing is often not implemented in mental health care," lead author added.

SOURCE: HealthDay News, February 2014

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Lymph Node Test a Good Strategy for Melanoma: Study

Testing a key lymph node in patients with the most dangerous form of skin cancer is the best approach to determine if the cancer has spread, new late-stage clinical research indicates. The test could significantly improve survival among those whose affected lymph nodes are then removed, the researchers said. Culminating nearly two decades of international research, the study provides the first long-term evidence affirming the value of a procedure known as "sentinel node biopsy" for intermediate and thick melanoma lesions, the study authors said. The study compared melanoma patients during a 10-year period. Among people with intermediate-thickness lesions, those whose lymph nodes were removed after their sentinel node biopsy tested positive for cancer were 44 percent more likely to survive their melanoma, said study author. The other "watchful waiting" group of patients didn't have their nodes removed until the disease was later found to have spread. "It makes sense: Those who were not treated up front had their melanoma spread from the sentinel lymph node to other lymph nodes in the area, [which can facilitate] a spread throughout the body," study author said. "This study provides concrete evidence that everything we had assumed about the sentinel node procedure ... and lymph node treatment is true." Initiated in 1994, the study randomly assigned about 2,000 patients with melanoma to two groups. The observation group had their lesion removed and their lymph nodes observed for recurrence, at which time they were removed. The biopsy group underwent lesion removal and a sentinel node biopsy, with immediate lymph node removal for patients whose cancer had spread to the sentinel node. In melanoma, a sentinel node biopsy removes the lymph node nearest a lesion and tests it for evidence of cancer. If the sentinel node is unaffected, the cancer is highly unlikely to have spread to surrounding lymph nodes or distant sites in the body. The biopsy procedure is also used in other malignancies, particularly breast cancer. In the new study's biopsy group, sentinel node results were the most important predictor for 10-year survival of melanoma among patients with lesions considered intermediate or thick. Disease-free survival rates over 10 years were significantly better in the biopsy group among patients with intermediate melanoma (about 71 percent compared with 65 percent) and thick melanoma (nearly 51 percent versus about 41 percent).

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