Unexpected long-term survival after low-dose palliative radiotherapy for non-small cell lung cancer

Many experienced oncologists have encountered patients with proven non-small cell lung cancer (NCLC) who received modest doses of palliative radiotherapy (RT) and who unexpectedly survived for > 5 years; some were apparently cured. We used a very large prospective database to estimate the frequency of this phenomenon and to look for correlative prognostic factors.

Patients with histologically or cytologically proven NSCLC, treated with palliative RT to a dose of < or = 36 Gy, were identified from a prospective database containing details of 3035 new patients registered from 1984-1990.

An estimated 1.1% (95% confidence interval, 0.7-1.6%) of 2337 palliative RT patients survived for 5 or more years after commencement of RT, including 18 patients who survived progression-free for 5 years. Estimated median survival was 4.6 months. Five-year survivors had significantly better Eastern Cooperative Oncology Group performance status at presentation than non-5-year survivors (P = 0.024) and were less likely to have distant metastases (P = 0.020). RT dose did not appear to be a significant prognostic factor. Patients who survived 5 years without progression had an estimated 78% probability of remaining free from progression in the next 5 years.

Approximately 1% of patients with proven NSCLC survived for > 5 years after palliative RT, and many of these patients appeared to have been cured by a treatment usually considered to be without curative potential. Because of the potential for long-term survival, doses to late-reacting normal tissues should be kept within tolerance when prescribing palliative RT in NSCLC.