Adding HT to RT Increases PFS in Locally Advanced Cancer

November 1, 2006

Patients withlocally advanced prostate cancer treatedwith radiotherapy and adjuvant hormonaltherapy gain as much as 12%longer progression-free survival (PFS),compared with those given radiotherapyalone, according to a large study of pooleddata reported at the 31st Congress of theEuropean Society for Medical Oncology.

ISTANBUL, Turkey--Patients withlocally advanced prostate cancer treatedwith radiotherapy and adjuvant hormonaltherapy gain as much as 12%longer progression-free survival (PFS),compared with those given radiotherapyalone, according to a large study of pooleddata reported at the 31st Congress of theEuropean Society for Medical Oncology(ESMO) (abstract 2 O).

Paolo Carlini, MD, of the ReginaElena Cancer Institute, Rome, Italy, presentedthe results of a pooled analysis of4,373 patients enrolled in seven randomizedphase III clinical trials of patientswith locally advanced disease designed todetermine if hormonal treatment plus radiotherapy decreases recurrence rate overradiotherapy alone. The researchers alsogathered data on overall survival and cancer-specific overall survival.

Two Statistical Models
To measure the impact of adding hormonaltherapy, the investigators used twodifferent statistical models--the fixedeffectand random-effect models (FEMand REM). FEM assumes that the trialsall have a similar true effect, while REMassumes that the true effect varies amongtrials around an unknown mean.

The study showed an absolute benefitin progression-free survival, overall survival,and cancer-specific overall survivalof 10.5%, 6.2%, and 3.3%, respectively,with the addition of hormonal therapy.The number of patients needed to treatfor one to benefit was 9, 16, and 30, respectively.The researchers also found thatlong-term hormonal therapy had agreater impact on progression-free survivalthan short-term treatment, with an overall benefit of 12% for long-termtherapy vs 9.3% for short-termtherapy.

The combination treatmentsignificantly decreasedrecurrence rates under boththe statistical models. Therelative risk (RR) under FEMwas 0.74 (P < .0001) and underREM, 0.69 (P < .0001). Similarly, overall survival was longer underboth models, with a relative riskof 0.84 under FEM (P < .001)and 0.81 under REM (P =.003). Cancer-specific overallsurvival was also significantlybetter for hormonal therapyusing FEM (RR 0.74, P = .001)and REM (RR 0.64, P = .023).

At a press briefing, study authorEmilio Bria, MD, of the Regina ElenaCancer Institute, speculated that severalfactors may have contributed to the benefitsseen with hormonal therapy. "Theincreased efficacy of radiotherapy in thepresence of hormone therapy may be dueto radiosensitization, to the reduction oflocal tumor burden, or perhaps to thekilling of occult disseminated cells outsidethe irradiated volume," he said.