Lung Cancer.pdf

Nonsurgical Treatment of Non–Small Cell Lung Cancer 145
gins—up to 3 cm, depending on the motion of the tumor. Fluoroscopy is
sometimes a poor predictor of tumor motion because the anteroposterior
and rotational motions can be significant. Furthermore, stage I lesions are
not well visualized under fluoroscopy. Ideally, in the future, PET or CT will
better define the GTV and CTV.
Radiation doses for T1 or T2 lesions are usually 60 Gy or higher. To find
the maximum tolerated dose with 3-dimensional conformal treatment, the
Radiation Therapy Oncology Group (RTOG) 93–11 trial (Table 8–1) has
been investigating dose escalation for small lesions ( 25% of the total
lung volume). Doses up to 90 Gy have been tolerated, although long-term
effects, such as cardiac damage, have started to appear. Whether a dose of
90 Gy results in better tumor control than that seen with lower doses ( 70
Gy) is not yet known. Patients with stage I disease who cannot be treated
with surgery usually have clinically staged disease; thus, survival comparisons
between these patients and surgically treated patients are difficult.
Several surgical series have demonstrated that 24% to 37% of patients
with clinical T1N0 or T2N0 disease have their disease upstaged on pathologic
examination after surgery, which explains the poor results in clinically
staged patients who are treated with radiation therapy alone. We analyzed
patients with stage I disease who were treated with radiation
therapy alone between 1980 and 1990 at M.D. Anderson Cancer Center
(Kupelian et al, 1996). Nineteen patients had clinical stage T1N0 NSCLC,
Table 8–1. Schema for Radiation Therapy Oncology Group Trial 93–11,
a Phase I/II Dose Escalation Study Using 3-Dimensional Conformal
Radiation Therapy in Patients with Inoperable NSCLC*
Group 1 ( 25% of total lung volume receives 20 Gy)
Dose level 1: 70.9 Gy in 33 fractions over 7–8 weeks (closed 1/8/98)
Dose level 2: 77.4 Gy in 36 fractions over 7–8 weeks (closed 9/23/98)
Dose level 3: 83.8 Gy in 39 fractions over 8–9 weeks (closed 12/20/99)
Dose level 4: 90.3 Gy in 42 fractions over 9–10 weeks (opened 12/20/99)
Group 2 (25% to 37% of total lung volume receives 20 Gy)
Dose level 5: 70.9 Gy in 33 fractions over 7–8 weeks (closed 6/14/99)
Dose level 6: 77.4 Gy in 36 fractions over 7–8 weeks (opened 6/14/99)
Dose level 7: 83.8 Gy in 39 fractions over 8–9 weeks
Group 3 ( 37% of total lung volume receives 20 Gy)
Dose level 8: 64.5 Gy in 30 fractions over 6–7 weeks (closed 7/1/99)
Dose level 9: 70.9 Gy in 33 fractions over 7–8 weeks (closed 7/1/99)
Dose level 10: 77.4 Gy in 36 fractions over 7–8 weeks (closed 7/1/99)
* All patients must have a completed 3-dimensional plan prior to entering this protocol.
Total lung volume is defined as the total volume of both lungs minus the PTV. Only 1
dose level per stratification group will open at a time. Dose prescription is to the ICRU 50
reference point.