Ten-year survival data of patients with high-risk cervical cancer
emphasize the need for extended-field irradiation, according to
the Radiation Therapy Oncology Group. The absolute survival was
55% for the patients who received the extended-field irradiation
vs 44% for patients treated with pelvic irradiation alone, data
from RTOG protocol 79-20 show.
Patients with stage IB or IIA primary cervical cancers measuring
4 cm or greater in diameter and patients with stage IIB cancers
were randomized to receive either standard pelvic irradiation
or pelvic plus para-aortic irradiation. There were 337 analyzable
patients in the study. "We believe the reason for the improved
survival was patients who completely responded to the extended-field
treatment had a lower incidence to distant metastases than their
counterparts treated on the other arm of the study," says
Marvin Rotman, MD, chair of the study. In addition, there was
a significantly better salvage rate in the complete responders
who later failed locally, he says.
Patients on the pelvic irradiation alone arm of the study received
40 to 50 Gy to the pelvic area in 4.5 to 6.5 weeks, 5 days a week.
Patients treated with para-aortic irradiation received 44 to 45
Gy delivered in 4.5 to 5.5 weeks, 5days a week. The pelvis then
received 20 Gy and the para-aortic fields were treated with an
additional 15 Gy.
All patients also underwent brachytherapy to a total dose of 4,000
to 5, 000 mg/h of radium equivalents.
Disease-free survival was similar in both arms (40% for the pelvic
irradiation alone arm and 42% for the pelvic plus para-aortic
irradiation arm). Locoregional failure rates also were similar
(35% for pelvic and 31% for pelvic plus para-aortic irradiation).
The cumulative incidence of grade 4 and 5 toxicities at 10 years
in the extended-field arm was 8.4%, as compared with 3.8% in the
pelvic irradiation only arm. Complications were found more often
in patients with prior abdominal surgery, Dr. Rotman says.