Studies that compared survival outcomes for at least four patients undergoing adrenalectomy for pathologically confirmed synchronous and metachronous metastases from non-small cell lung cancer to the adrenal gland and surgical resection for the primary cancer were eligible for inclusion. Patients with metastasis to other organ sites were excluded, except for those who had undergone resection or definitive radiation of solitary brain metastases. Studies were excluded if the inclusion criteria could not be verified or did not specify the time interval from adrenalectomy until the last follow-up or death.
Synchronous metastasis was defined as a disease-free interval of six months or less. Disease-free interval was defined as the time interval between the date of primary lung cancer resection and the confirmed diagnosis of adrenal metastasis.
Patients in the synchronous metastasis group had a median age of 54 years (range 40 to 63); two thirds were male. The median disease-free interval in this group was 0 months (range 0 to 6 months), the median diameter of metastases was 53cm (range 8 to 150sm), and none of the patients for whom the data were reported had synchronous brain metastasis.
Patients included in the metachronous metastasis group had a median age of 68 years (range 44 to 78); most were male. Their median disease-free interval was 12 months (range 7 to 38 months), the median diameter of metastases 71cm (range 15 to 150cm), and two patients had synchronous brain metastasis. No patients were symptomatic from adrenal metastases.
The authors did not state how the reviewers made decisions on the selection of primary studies.