Late rectal toxicity after prostate radiation- a ‘dynamic process’
MedWire News: The development of late rectal toxicity after radiotherapy for prostate cancer is a “dynamic process,” with different time courses for rectal bleeding and fecal incontinence, study findings show.
Researchers observed that, over time, rectal bleeding symptoms improved while fecal incontinence worsened.
K Odrazka, from Pardubice Regional Hospital in Kyjevska, Czech Republic, and colleagues, examined the timing of late rectal toxicity, its profile, and behavior over time in a cohort of prostate cancer patients treated with three-dimensional conformal radiation therapy (3D-CRT).
“Even with advanced radiotherapy techniques, it is not feasible to completely spare [the rectum] because of microscopic disease extension, physiological prostate movement and set-up uncertainties,” they explain in the journal Prostate Cancer and Prostatic Diseases.
The cohort of 320 patients had stage T1/T2 and T3 disease, and were treated with 70 and 74 Gy 3D-CRT, respectively. Living patients (n=228) were followed-up for a median of 7 years, with gastrointestinal (GI) and genitourinary symptoms charted using the Radiation Therapy Oncology Group and Late Effects Normal Tissue Task Force toxicity criteria.
The patients had an average risk for grade 2 and 3 rectal toxicities of 10.0% and 3.9%, respectively, 2 years after treatment, and an estimated 15.6% and 7.0% risk, respectively, after 5 years, with rectal bleeding the most common symptom.
The majority (80%) of patients experienced no or mild (grade 1) GI toxicity, and no fatal or grade 4 GI toxicities were observed during follow-up.
The proportion of rectal bleeding among GI toxicities reduced from 85% at 1.5 years after treatment, to 46% at 4.5 years, while the opposite occurred for fecal incontinence, which increased from 0% at 1.5 years to 27% at 4.5 years.
Although the overall prevalence of rectal symptoms declined over time, the researchers saw two peaks in grade 2 and 3 toxicity, at 1.5 and 4.5 years, and 2 and 5 years, after treatment respectively.
Odrazka et al attribute this to the initial increase and subsequent decline in rectal bleeding, and gradual increase in fecal incontinence.
“Rectal toxicity is undoubtedly a dynamic process,” the team concludes. “Rectal bleeding is fairly manageable and the rate of fecal incontinence is low.”
They hope that “advanced radiotherapy techniques will significantly contribute to further reduction of rectal toxicity.”
MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010
By Sarah Guy