prostate news

IGRT May Improve Outcomes for Obese Prostate Cancer Patients

September 2, 2009—Moderately to severely obese prostate cancer patients may have improved treatment outcomes when treated with image-guided radiation therapy (IGRT) over traditional external beam radiation therapy (EBRT) because IGRT corrects for prostate shifts, which, if not planned for, can lead to incorrect doses of radiation to the disease site, according to a study in the September 1 issue of the International Journal of Radiation Oncology*Biology*Physics, the official journal of the American Society for Radiation Oncology (ASTRO).

Several studies have suggested that obesity can lead to higher rates of clinical recurrence or biochemical failure rates in prostate cancer patients receiving EBRT. Researchers at the Carol G. Simon Cancer Center, Morristown Memorial Hospital in Morristown, N.J., and the Uematsu-Atsuchi-Serendipity Oncology Center in Terukuni, Kagoshima, Japan, sought to determine if these failure rates were caused by the treatment modality used rather than strictly the fact that the patients were obese.

Researchers found that moderately to severely obese prostate cancer patients (i.e., with a body mass index of greater than 35) do have larger prostate shifts during treatment, which can lead to radiation treatments not being delivered to the same spot every day, potentially compromising the treatment. The percentage of moderately to severely obese patients with a left to right shift of greater than 10 millimeters was 21.2 percent compared to only 1.3 percent for patients of a normal weight.

IGRT is a new type of radiation therapy that uses normal EBRT guided by imaging, such as CT scans, ultrasound or X-rays taken in the treatment room just before the patient is given radiation on a daily basis. All patients receive imaging scans as part of the planning process. However with IGRT, doctors are able to compare the earlier images with those taken before each treatment to adjust the dose if necessary.

Researchers determined that the radiation treatment modality used does impact outcomes. IGRT allows for correction of target displacements from the planned position before radiation delivery begins, so shifts may be corrected easily and thus may lead to improved control rates for obese prostate cancer patients.

“All patients deserve the treatment that is going to give them the best chance at cure and survival,” James R. Wong, M.D., lead author of the study and chair of radiation oncology at Morristown Memorial Hospital, said. “With the results of this study, we now know that obese patients have a unique complication when it comes to planning their treatment but that we can try to correct it simply by using IGRT instead of EBRT. I encourage overweight men and their families to talk to their doctors about IGRT when considering their treatment options.”

ASTRO is the largest radiation oncology society in the world, with more than 10,000 members who specialize in treating patients with radiation therapies. As the leading organization in radiation oncology, biology and physics, the Society is dedicated to improving patient care through education, clinical practice, advancement of science and advocacy. For more information on radiation therapy, visit www.rtanswers.org. To learn more about ASTRO, visit www.astro.org.

Weight Gain in Adulthood Associated with Prostate Cancer Risk; Patterns Differ by Ethnicity

• Overweight by age 21 linked to lower risk of localized, low-grade prostate cancer
• Overweight in older adulthood linked to increased risk of prostate cancer
• Risk varied across ethnic groups

September 1, 2009 – Body mass in younger and older adulthood, and weight gain between these periods of life, may influence a man’s risk for prostate cancer. This risk varies among different ethnic populations, according to results of a study in Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research.

“The relationship of certain characteristics, such as body size, with cancer risk may vary across ethnic groups due to the combined influence of both genes and lifestyle,” said lead researcher Brenda Y. Hernandez, Ph.D., M.P.H., assistant professor at the Cancer Research Center of Hawaii, University of Hawaii.

Obesity is a risk factor for common cancers like colorectal cancer and breast cancer in post-menopausal women. However, the influence of body size on prostate cancer risk is not entirely understood. Hernandez and colleagues examined this relationship in a multiethnic population consisting of blacks, Japanese, Hispanics, Native Hawaiians and whites, and compared differences among age groups. They used the Multiethnic Cohort, a longitudinal study of men aged 45 to 75 years old established in Hawaii and California from 1993 to 1996.

Results showed that of the 83,879 men who participated in this study, 5,554 were diagnosed with prostate cancer. Overall, men who were overweight or obese by age 21 had a decreased risk of localized and low-grade prostate cancer, according to Hernandez.

Being overweight in older adulthood was associated with increased risk of prostate cancer among white and Native Hawaiian men, but a decreased risk among Japanese men. Excessive weight gain between younger and older adulthood increased the risk of advanced and high-grade prostate cancers in white men and increased the risk of localized and low-grade disease in black men, but decreased the risk of localized prostate cancer in Japanese men.

“Readers of Cancer Epidemiology, Biomarkers & Prevention might initially look at these results and discount them for being inconsistent across the racial/ethnic groups, but they should not,” said Elizabeth A. Platz, Sc.D., M.P.H., associate professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health, Baltimore.

Platz stressed the strengths of this study, including that it was conducted prospectively and consisted of large numbers of men in most of the ethnic groups studied. An estimated 30 percent of prostate cancer cases occurred among Japanese men (n=25,275), 25 percent among white men (n=21,311), 27 percent among Hispanic men (n=20,448), 13 percent among black men (n=10,934), and 7 percent among Native Hawaiian men (n=5,921).

“There is no reason to think that the differences in results by ethnicity are explained by bias. Different racial and ethnic populations tend to have differing proportions of fat relative to lean mass and carry their fat mass differently. These differences may be used as a launching point for the next line of research: The nature of the weight gain — amount of fat gained and distribution of the fat gained in association with prostate cancer risk overall, and by stage and grade,” added Platz, who is also an editorial board member for Cancer Epidemiology, Biomarkers & Prevention.
This study underscores the importance of investigating cancer etiology in diverse populations and researchers should conduct additional studies.

“These results do not warrant a change in the current public health messages about obesity: Men of normal weight in all racial/ethnic groups should be encouraged to avoid weight gain and men who are overweight and obese should be encouraged to lose weight for good health in general,” Platz added.

Drug For Urination Difficulties Linked With Complications After Cataract Surgery

May 19, 2009 — Use of the medication tamsulosin to treat male urination difficulties within two weeks of cataract surgery is associated with an increased risk of serious postoperative ophthalmic adverse events such as retinal detachment or lost lens, according to a study in the May 20 issue of JAMA.

Benign prostatic hyperplasia (BPH; enlarged prostate) affects nearly 3 of 4 men by the age of 70 years, with symptoms of BPH including urination difficulties. A commonly prescribed medication for BPH is tamsulosin, which accounted for more than $1 billion in sales in 2007, according to background information in the article. Some research has suggested that this drug may increase the risk of complications, such as intraoperative floppy iris syndrome (IFIS) during cataract surgery, a procedure that approximately 5 percent of elderly U.S. residents undergo every year. “However, few studies have been large enough to assess the connection between tamsulosin exposure and postoperative complications,” the authors write.

Chaim M. Bell, M.D., Ph.D., of St. Michael’s Hospital, Toronto, Canada, and colleagues conducted a large, population-based analysis of postoperative adverse events experienced by patients who were prescribed tamsulosin or other alpha-blockers at the time of cataract surgery. Using linked health care databases from Ontario, Canada, the study included 96,128 men, age 66 years or older, who had cataract surgery between 2002 and 2007.

Of the patients in the study, 3,550 (3.7 percent) had recent (within 14 days of cataract surgery) exposure to tamsulosin and 1,006 (1.1 percent) had previous (more than 14 days before cataract surgery) exposure to tamsulosin. There were 7,426 patients (7.7 percent) who had recent exposure to other alpha-blocking medications and 1,683 (1.1 percent) who had previous exposure. The researchers identified 284 case patients (0.3 percent) who experienced an adverse event in the 14 days after surgery. Of these 284 cases, 175 had a procedure for lost lens or lens fragment, 35 for retinal detachment, and 26 had both. One hundred had suspected endophthalmitis (inflammation within or around the eye). Of the 284 cases, 280 were matched to 1,102 control patients.

In the analysis of adverse events following cataract surgery, patients who received tamsulosin in the 14 days before surgery had a 2.3 times higher risk of a serious adverse event (7.5 percent vs. 2.7 percent of controls). For patients prescribed other alpha-blockers, 7.5 percent of case patients and 8.0 percent of control patients received the medication in the 14 days preceding surgery. Those who had previous exposure to tamsulosin were not at elevated risk for complications, as where patients who had previous exposure to other alpha-blockers.

“We believe that this is the first large study with an adequate study design to describe this effect [that tamsulosin exposure is associated with an increased risk of postoperative complications] and provide a population-based risk estimate (something that can only be done using population-based observational research). It is unclear whether drug discontinuation prior to surgery reduces this risk. Because the combination of cataract surgery and tamsulosin exposure is relatively common, patients should be properly appraised of the risks of drug therapy and preoperative systems should focus on the identification of tamsulosin use by patients. In this way, surgeons can plan and prepare for a potentially more complicated procedure or refer to someone with more experience,” the authors conclude.

Editorial: Tamsulosin and the Intraoperative Floppy Iris Syndrome

In an accompanying editorial, Alan H. Friedman, M.D., of the Mount Sinai School of Medicine, New York, comments on the findings of Bell and colleagues.

“Cataract surgery is the most commonly performed operation in the United States today. With nearly 2 million cataract operations performed in the United States each year, the magnitude of IFIS associated with tamsulosin cannot be underestimated. Although the prescribing information for tamsulosin includes IFIS as a ‘general precaution,’ the data on the risk of this complication should be reassessed to determine whether a ‘black box’ warning should be issued to caution the ophthalmic surgeon and the general public (men in particular) of danger to the eye of taking alpha1-adrenergic blocking agents before cataract surgery.”