To evaluate the use of radiotherapy in treating lung cancer.

MEDLINE was searched for 3 years for lung cancer with 'radiotherapy' as a MESH term, and for the previous 10-year period an additional subheading of 'randomized trial'. In addition, the PDQ database and recent reference books were searched. Articles occurring frequently as references in the literature were included. Searches were updated to include articles up to 1993.

Study designs of evaluations included in the review

No design criteria were given. The included studies were classified into: meta-analysis, phase 3 studies, phase 1 and 2 studies, retrospective studies, reviews and other studies (including case studies, letters, editorials and comments).

Specific interventions included in the review

Radiotherapy for lung cancer alone or as an adjunct to chemotherapy or surgery.

Participants included in the review

The participants were patients with small-cell lung cancer (SCLC) and non-small-cell lung cancer (NSCLC).

Outcomes assessed in the review

Local tumour control, relapse and survival were assessed.

How were decisions on the relevance of primary studies made?

One reviewer read and classified the studies. A second reviewer and, where necessary, up to two external reviewers, commented on preliminary drafts of the review. No additional information was provided.

Scientific quality was assessed on a three-level scale (high/moderate/low), based on SBU recommendations for evaluation, with weighting based on rigour of study methodology. One reviewer read and classified the studies. A second reviewer and, where necessary, up to two external reviewers, commented on preliminary drafts of the review. No additional information was provided.

The author does not state how the data were extracted for the review, or how many of the reviewers performed the data extraction.

How were the studies combined?

The studies were combined in a narrative review.

How were differences between studies investigated?

A subgroup analysis by tumour type was performed.

There were 80 articles (28,172 patients) including 2 meta-analyses (4,014 patients), 29 randomised studies (6,947 patients), 19 prospective studies (1,144 patients) and 21 retrospective studies (16,067 patients).

SCLC limited stage disease: treating these patients with combination radiotherapy and chemotherapy both reduces the number of local recurrences and increases overall survival.

SCLC extensive stage disease: Published data do not show that the addition of radiotherapy leads to improved patient survival in this group.

NSCLC stages I and II: Surgery is accepted as the primary treatment strategy. No evidence suggests that post-operative radiotherapy extends survival.

NSCLC stage III: The studies suggest that radiotherapy improves short-term (2 & 3 years) survival in this group, but gains in 5-year survival are doubtful.

Prophylactic cranial irradiation (PCI): For brain metastases, this appears to substantially reduce the risk of symptomatic brain metastases from SCLC but not NSCLC. No studies confirmed that treatment affects survival.

Palliative treatment of associated symptoms: Radiotherapy appeared to be highly effective in easing symptoms (severe cough, severe bleeding, pain, pulmonary obstruction and vena cava superior syndrome) during much of a patient's remaining life.

The quality of literature addressing radiotherapy for lung cancer is relatively good. It includes several randomised studies with reasonable numbers of patients.

Radiotherapy may provide an alternative for patients with NSCLC stages I and II, who are inoperable for medical reasons. The value of radiotherapy following radical surgery for NSCLC remains to be shown and is not indicated based on current knowledge. For NSCLC stage III, radiotherapy prolongs survival at 2 and 3 years but in view of the side-effects it is questionable whether this is of benefit. Attempts to add chemotherapy to radiotherapy in treating NSCLC have as yet not yielded convincing results, but several studies are in progress.

PCI greatly reduces the risk for brain metastases from SCLC and many treatment centres give PCI to SCLC patients who have achieved complete remission. In view of the serious complications associated with PCI, this practice may be questioned.

The review adequately states its objective, interventions, participants, outcomes, validity criteria and results. The search strategy is clearly stated but is restrictive. The review lacks sufficient detail on the process by which inclusion and validity criteria were applied, methods of data extraction, combining of results and assessment of the differences between the studies. The results appear to accurately reflect the evidence presented.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.