MIAMI BEACH – For women with cervical cancer, intensity-modulated radiation therapy to the pelvis after surgery provides disease control similar to that seen with standard external beam radiation therapy, but with lower acute bowel toxicity, investigators reported here.
Two-year results from the phase II Radiation Therapy Oncology Group (RTOG) 0418 trial showed that the combination of the newer radiation technique and weekly cisplatin chemotherapy was associated with an estimated disease-free survival rate of 86.9%. This compares with historic data, Dr. Lorraine Portelance told attendees at the annual meeting of the American Society for Radiation Oncology (ASTRO).
Dr. Lorraine Portelance
The RTOG investigators had previously reported that pelvic intensity-modulated radiation therapy (IMRT) to 50.4 Gy delivered over 28 fractions plus weekly cisplatin 40 mg/m2 with or without vaginal brachytherapy was associated with a significant reduction in grade 2 or greater short-term bowel toxicity compared with historical controls.
"One very important question remained, though: were we able to achieve decreased toxicity and good chemotherapy compliance at a cost of disease control loss? We have now reached the point where we could analyze the secondary end point of disease control, which is of prime importance to determine if this disease approach is viable," said Dr. Portelance from the University of Miami’s Sylvester Comprehensive Cancer Center.
A total of 40 patients from 25 institutions were eligible for analysis of the secondary end point. All had hysterectomies (3 total abdominal, 3 vaginal, 28 radical, and 6 laparoscopic assisted).
Two patients (5%) had International Federation of Gynecologists and Obstetricians (FIGO) stage IA disease; 31 (77.5%) had stage IB; 4 (10%) had stage IIA; and 3 (7.5) had stage IIB disease. In 25 patients there was no nodal involvement; 15 had 1 involved node.
At a median 2.68 years’ follow-up, there were 5 local-regional relapses (estimated 2-year rate, 10.6%); 3 para-aortic nodes involved (5.3%); and 4 distant metastases (excluding the para-aortic nodes; 10.3%).
Dr. Portelance noted that this translated into an estimated 2-year disease-free survival rate of 86.9%, which is comparable to that shown in an intergroup trial, published in 2000, that compared concurrent chemotherapy and pelvic radiation therapy with pelvic radiation therapy alone as adjuvant therapy after radical surgery in high-risk early-stage cervical cancer (J. Clin. Oncol. 2000;18:1606-13).
In the RTOG 0418 trial, the estimated 2-year overall survival rate is 94.6%, again comparable with previously published data, Dr. Portelance said.
"This ROTG 0418 study provides level II evidence that, when done under clear guidelines, postoperative pelvic intensity-modulated radiation could lead to decreased toxicity and excellent chemotherapy without any cost in disease control," she concluded.
The study was supported by grants from the National Cancer Institute. Dr. Portelance said she had no conflicts of interest.