NEW ORLEANSPositron emission tomography (PET) scanning is a
powerful predictor of survival in patients with non-small-cell lung
cancer (NSCLC), reported Michael MacManus, MD, of the Peter MacCallum
Cancer Institute, East Melbourne, Australia.
The prospective study, presented at the 36th Annual Meeting of the
American Society of Clinical Oncology (ASCO), included 56 patients
with inoperable stage IA to IIIB disease. Patients underwent
concurrent platinum-based radical chemoradiotherapy (44 cases) or
radical radiotherapy alone (12 cases) and PET and CT scans.
Pretreatment and post-treatment scans were coregistered on a screen,
and response was evaluated qualitatively by a nuclear medicine
physician. Data were recorded prospectively before the patients
clinical response was known.
As background, Dr. MacManus reminded oncologists that PETs
superiority to CT-based staging in operable lung cancer is already
recognized. PET is also superior to conventional staging in
candidates for radical radiotherapy and has shown promise in
evaluating patients after treatment.
Thoracic CT scanning, on the other hand, is difficult to interpret
and correlates rather poorly with outcome after radical radiotherapy.
One of the aims of the study was to determine a better means of
predicting which patients could benefit from additional therapy after
In many cases, PET scanning revealed information that was different
from that obtained by CT scanning. By PET scanning, about half of the
patients who appeared to have a complete treatment response on CT
scan had evidence of residual tumor, and some patients who
demonstrated tumors on CT actually had a complete response on PET,
Dr. Mac-Manus said.
We treated some patients who had PET evidence of metastases,
unconfirmed by other means, with radical therapy, and they all failed
at sites of PET-detected metastases, so we dont do that
anymore, he said. We generally believe the PET scan.
One-year survival was 58%, and 2-year survival 48%. Complete
responses were seen by PET scans in 43% of patients; a partial
response was seen in 41%; stable disease was noted in 7%, and disease
progressed in 9%.
PET scanning predicted survival. Actuarial survival was 84% at both 1
and 2 years for the 24 patients (43%) who achieved a complete
response on PET, and 43% and 31%, respectively, for the patients who
did not achieve a complete response. Median survival for all patients
was 14 months. Survival was strongly correlated with a favorable
response by PET scan; it was not correlated with chemotherapy response.
Dr. MacManus gave the mortality hazard ratios from the multivariate
analysis according to the patients response on PET scan: 1.0
for complete response, 2.97 for partial response, 3.92 for no
response, and 78.7 for progressive disease. These results were highly
statistically significant, he said.
Dr. MacManus concluded, PET response to radical
chemoradiotherapy separates patients into groups with widely
differing survival probabilities. Early CT scanning results did not
correlate strongly with survival. Response less than a complete
response was associated with relatively poor survival. PET may
identify patients who are suitable for salvage therapy, but we need
longer follow-up to see what happens with these patients.