Pulmonary metastatic melanoma -- the survival benefit associated with positron emission tomography scanning

Positron emission tomography (PET) scanning is more sensitive at detecting metastatic disease than conventional radiological techniques. For patients with pulmonary metastatic melanoma, we investigate if PET scanning to detect occult extra pulmonary disease prior to thoracotomy and metastectomy is associated with improved survival compared to patients staged by conventional radiology.

Between November 1984 and December 1999, 121 patients (90 males, 31 females) have undergone a thoracotomy and pulmonary metastectomy for metastatic melanoma. The age range was 19-84 years (mean 57, median 59). In every case all palpable nodules were removed and the diagnosis confirmed histologically. A total of 68 (56%) patients had a PET scan preoperatively, 53 (44%) underwent conventional or nuclear imaging. Patients with only radiologically isolated pulmonary disease are included.

Survival is 100% complete and totals 238 pt/years (mean 2.2 years, median 1.4 years). Survival (+/-SE) at 1, 3, 5 and 7 years for all patients is 68% (+/-4.5) (n=67), 36.6% (+/-5.2) (n=27), 22.1% (+/-4.8) (n=15) and 13.5% (+/-4.2) (n=7), respectively. Survival (+/-SE) was significantly better at 3 and 5 years in patients who underwent a PET scan preoperatively (Log rank P=0.002). There was no significant difference in survival by 7 years.

There is a significant survival benefit associated with excluding extra pulmonary disease using a PET scan prior to thoracotomy and metastectomy. We recommend that PET scanning be used in the investigation of patients with pulmonary metastatic melanoma prior to metastectomy.