Surgery versus stereotactic radiotherapy for patients with early‐stage non–small cell lung cancer

The treatment of early-stage non-small cell lung cancer (NSCLC) continues to pose a major challenge, as reflected by disappointing 5-year disease-free survivals rates of only 69% in patients in a randomized trial who underwent surgery and mediastinal lymph node dissection. Significant surgical toxicity continues to be noted in unselected patient populations, and centralization of surgical resections to high-volume centers may not reduce 30-day mortality rates. It is interesting to note that 90-day mortality rates are approximately twice those of the more commonly cited 30-day figures. Analysis in nearly 1300 patients who underwent surgery for early-stage NSCLC revealed a risk of disease recurrence ranging from 6% to 10% per person-year during the first 4 years after surgery. Challenges facing long-term survivors include the finding that> 50% of all deaths in 5-year survivors of NSCLC are also related to lung cancer, with a persistent risk of death from lung cancer observed up to 18 years from the time of diagnosis. Recent data indicate a far higher incidence of second primary lung cancers in this patient group than was previously appreciated. Although an anatomical resection is accepted as the standard of care in patients with early-stage NSCLC, a significant percentage of elderly patients do not undergo any local therapy. Changing demographics of lung cancer have resulted in the elderly now representing the fastest growing patient subgroup. Comorbidities are more common in the elderly, and comorbidity in elderly patients with lung cancer is associated with higher overall mortality. It is in the latter patient subgroups that stereotactic ablative radiotherapy (SABR, or SBRT) has had a major impact on population survival rates. SABR is typically characterized by the use of 4-dimensional radiotherapy planning scans and the delivery of high doses of radiotherapy ranging from 7.5 Grays to 18 Grays, typically in 3 to 8 once-daily fractions delivered with a high degree of precision. Current evidence suggests that SABR can be considered to be the preferred treatment in patients who are unfit for surgery. Population-based studies revealed disappointing survival after conventionally fractionated radiotherapy delivered in 30 fractions. A study that was conducted after the introduction of SABR into the Dutch population revealed an improvement in the median survival of 9.3 months in patients aged 75 years who underwent radiotherapy. SABR has been used mainly for patients with peripheral lung tumors who are unfit to undergo surgery. However, retrospective studies in patients who underwent SABR despite being fit to undergo surgery have reported 5-year overall survival rates in the range of 51% to 70%. These reports, together with the low reported toxicity of SABR, have led to interest in trials comparing both treatments, but these prospective trials have either failed to accrue patients or are doing so at a pace that is unlikely to provide any answer in the near future. In such a situation, propensity scorematched pair analysis can be used to obtain 2 comparison groups with similar known prognostic factor characteristics. The propensity score is the conditional probability of assignment to a particular treatment based on several factors or covariates (eg, sex, age, cTNM stage, etc). The score, ranging from 0 to 1, assigns a probability of having received a particular condition (eg, SABR) to each patient, and adjustment for the scalar propensity score can remove bias due to all observed covariates.