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IMPLICATIONS FOR MANAGING PROSTATE CANCER AND KIDNEY CANCER HIGHLIGHTED AT ASCO GU PRESSCAST

ORLANDO, FL – Three studies with implications for managing patients with prostate cancer and kidney cancer were featured at a pre-meeting Presscast of the 2013 Genitourinary Cancers Symposium sponsored by ASCO, ASTRO, and SUO. The main findings of the respective studies are:

  • Prostate cancer found in African-American men and older men is more likely to be high-risk disease.
  • Men with high-risk prostate cancer treated with radiation plus anti-androgen therapy can be safely treated with 18 months of androgen blockade instead of 24 – 36 months.
  • Elderly patients with small kidney masses have similar cancer-related survival with surveillance versus surgical resection.

High-Risk Prostate Cancer

About 40% of cases of high-risk, PSA-detected prostate cancer occur in men over the age of 75 years, and elderly men are 9.4 times more likely than men under the age of 50 to be high risk. African-American men of any age are more likely than white men to have high-risk disease. These findings of a large, population-based, retrospective study are among the first to suggest that PSA testing can identify high-risk prostate cancer.

Early, asymptomatic prostate cancer is not detectable on physical exam. The study suggests that PSA testing may be warranted in elderly and African-American men, but more research is needed to show that early detection and treatment can improve outcomes.

“If we stop PSA screening altogether [as recommended by the U.S. Preventive Services Task Force], there is no other method to detect this form of prostate cancer sufficiently early to have the best chance of helping this group of high-risk patients. The findings of this study will help physicians and certain patients make more informed decisions on whether or not they want to proceed with PSA testing, although more research (and longer follow-up) is needed to determine the effects of early detection and intervention on outcome in these high-risk patients,” stated lead author Hong Zhang, MD, PhD, University of Rochester, Rochester, NY.

The study used SEER data to identify 70,345 men with early-stage (T1C), node-negative, prostate cancer diagnosed between 2004 and 2008. The investigators determined the probability of developing low-, intermediate-, and high-risk prostate cancer based on PSA criteria and Gleason stage.  Low risk was defined as PSA < 10 mg/L and Gleason score of 6 or lower; intermediate risk was defined as PSA 10-20 mg/L and/or Gleason 7; and high-risk disease was defined as PSA of 20 or higher mg/L and/or Gleason score of 8 or higher; 47.6% were found to have low-risk disease; 35.9% intermediate-risk, and 16.5%, high-risk.

Men over the age of 75 accounted for 11.8% of this population, but comprised 24.3% of intermediate- and 26.1% of high-risk disease.

Shortened Duration of Hormone Therapy for High-Risk Prostate Cancer

Patients with high-risk prostate cancer treated with radiation had similar survival with 18 months of hormone therapy compared with 36 months of hormone therapy, according to results of a randomized Phase III study.

Given the compromising effects of hormone therapy on quality of life, “shorter-term hormone therapy could have a big impact on the lives of men with prostate cancer, reducing the quantity and intensity of its unpleasant side effects as well as treatment costs. We hope these results will convince doctors that they can stop hormone therapy after 1.5 years instead of 2 to 3 years,” stated lead author Abdenour Nabid, MD, Centre Hospitalier de Universitaire de Sherbrooke in Sherbrooke, Canada.

The optimal duration of androgen ablation therapy in high-risk prostate cancer remains in question. The study randomized 630 patients with node-negative, high-risk prostate cancer to radiotherapy to the pelvic area and prostate bed plus 18 months of androgen ablation therapy versus 36 months of androgen ablation therapy (biculatamide 1 month plus goserelin every 3 months).

Demographic and disease characteristics of the study population were well balanced between the two arms. Median age was 71 years, median PSA was > 20/ng/ml, and median Gleason score was > 7.  Most patients had stage T3 or T4 disease.

At a median follow-up of 77 months, no difference in mortality was found between the two-arms:22.9% in the shorter-duration hormone therapy arm versus 23.8% in the longer-duration arm. Of these deaths, 116 patients died of causes other than prostate cancer.

At 5 years, overall survival rates were 92.1% versus 86.8% for the 2 arms, respectively, and 10-year survival rates were 63.6% versus 63.2%, respectively. Disease-specific survival rates at 5 years were 97.6% versus 96.4%, respectively, and 10-year disease-specific survival rates were 87.2% in both arms.

Small Renal Masses in Elderly Can Be Managed by Surveillance

Small kidney masses identified in elderly patients can be safely managed by surveillance, avoiding the need for surgical resection.

A retrospective analysis of more than 8300 elderly patients with small kidney masses showed that kidney cancer-specific mortality was comparable with surveillance or surgical resection of the masses. Moreover, the study found that patients managed with surveillance had a lower risk of cardiovascular complications and death from all causes.

“Our analysis indicates that physicians can comfortably tell an elderly patient, especially a patient that is not healthy enough to tolerate anesthesia and surgery, that the likelihood of dying of kidney cancer is low and that kidney surgery is unlikely to extend their lives. However, since it is difficult to identify which tumors will become lethal, elderly patients who are completely healthy and have an extended life expectancy, may opt for surgery,” stated lead author William C. Huang, MD, New York University Medical Center, New York City.

The study was based on SEER registry data linked to Medicare claims for patients aged 66 or older diagnosed with small renal masses (i.e., under 1.5 inches in diameter). Of 8317 patients, 5706 (70%) underwent surgery and 2611 (31%) underwent surveillance. At a median follow-up of 4.8 years, 2078 deaths were reported (25% of the population); 277 deaths (3%) were due to kidney cancer.  The rate of kidney cancer-specific death was similar between the surveillance and surgery groups.

After controlling for patient and disease characteristics, patients who had surveillance had a significantly lower risk of death from any cause as well as a lower risk of a cardiovascular event.

The authors conclude that surveillance with modern imaging techniques is a safe option for management of small renal masses in elderly patients.

by Alice Goodman

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