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HIGH DOSE RADIOTHERAPY FOR NON-SMALL-CELL CANCER
OF THE LUNG
ShiaoY.Woo,M.D.
Radiation Oncology, The Methodist
Hospital, Baylor College of Medicine, Houston, TX
It is established that for early stage resectable non-small-cell lung cancer,
surgery is more effective than radiotherapy; however, radiotherapy alone has
cured a small number of patients with potentially resectable but medically inoperable
cancer.' 1
' Postoperatively, radiotherapy has been used to treat the surgical
bed in cases of close or positive margins, and to treat the regional lymph nodes
in cases of positive mediastinal node metastasis. At least one randomized study
showed an improved disease-free survival for radiotherapy in the latter situation.'
21
The most common application of radiotherapy in the therapy of nonsmall-cell
lung cancer is to palliate symptomatic metastases or to treat the primary
unresectable disease when there is no obvious distant metastasis. The
long-term outcome of most patients with Stage III non-small-cell lung cancer is
poor despite the comprehensive radiotherapy. Several radiotherapeutic regimens
have been studied as attempts to improve the prognosis.
In the 70's the Radiation Therapy Oncology Group (RTOG) performed a
four-arm trial to establish a dose response relationship in the treatment of nonsmall-cell
lung cancer.' 31
The patients were randomized to 4000 cGy split course
(2000 cGy in 5 fractions, two weeks rest and then repeat 2000 cGy in 5 fractions),
4000 cGy continuous, 5000 cGy continuous, or 6000 cGy continuous treatment at
200 cGy per fraction. The two-year survival rate for 6000 cGy was better than
that for 4000 cGy (19% versus 10%). Local control was 61% for 6000 cGy and
48% for 4000 cGy. This trial established the standard total radiation dose for conventional
radiotherapy of non-small-cell lung cancer.
Since clinical failure patterns' 41
and autopsy studies' 51
suggested that local
tumor progression was an important element leading to death in these patients,
it appeared logical to explore higher total dose of radiation to improve loco-regional
control. Based on radiobiological principles, if one wants to increase the
total radiation dose but not to increase late toxicities, one needs to reduce the
radiation dose-per-fraction. If the radiation dose-per-fraction is reduced, more
than one treatment per day can be delivered so that the overall treatment time is
not unduly delayed. Such a radiotherapy schedule is called hyperfractionated
radiotherapy. Hyperfractionated regimens using 120 cGy twice a day for the
treatment of Stage III non-small-cell lung cancer were initiated in 1983 by the
RTOG. Patients were randomized to receive minimal total doses of 6000,6480,
6960,7440, and 7920 cGy.' 61
For patients with favorable stage III disease
(Karnofsky performance status 70-100, less than 6% weight loss) a dose response
was found for survival: survival with 6960 cGy (median 13 months 2 year 29%)
was significantly (P=0.02) better than the lower total doses. There was no differ-
S/xTH INTERNATIONAL SYMPOSIUM ON AUTOLOGOUS BONE MARROW TRANSPLANTATION 179