RESUMO
OBJECTIVES: The purpose of this study was to determine the frequency, characteristics, and survival of second primary lung cancer initially identified as an indeterminate lesion on the original computed tomography scan and then diagnosed during the surveillance period in a prospective study. METHODS: A prospective database of 271 patients enrolled in a surveillance study was updated. Indeterminate lesions present on the original computed tomography at the time of initial primary lung cancer diagnosis that subsequently grew and were diagnosed as cancer were termed "synchronous primary lung cancer." Lesions that were not present on the original computed tomography scan and subsequently diagnosed on surveillance were termed "metachronous primary lung cancer." RESULTS: Thirty patients (11.1%) developed 37 second primary lung cancers over a median surveillance period of 84.7 (range, 15.9-147.6) months. Of these, 15 of 37 (40.5%) were identified as synchronous primary lung cancer, and 22 of 37 (59.5%) were identified as metachronous primary lung cancer. At first identification, ground-glass lesions were identified in 9 of 15 (60%) synchronous primary lung cancers compared with only 5 of 22 (22.7%) of metachronous primary lung cancers (P = .034). Compared with metachronous primary lung cancer, from first identification to diagnosis, synchronous primary lung cancer developed over a longer interval (33.6 vs 7.2 months, P = .001) and had a slower growth rate (0.17 vs 0.45 mm/month, P = .027). The 5-year overall survival from second lung cancer was 73.0%. No significant differences were observed between the synchronous primary lung cancer and metachronous primary lung cancer cohorts in overall survival from initial primary lung cancer (P = .583) or from second lung cancer (P = .966). CONCLUSIONS: Computed tomography surveillance identifies 2 types of curable second lung cancers leading to excellent overall survival.
RESUMO
OBJECTIVES: A minimal-dose computed tomography scan of the thorax (MnDCT) delivers a radiation dose comparable with a chest x-ray (CXR). We hypothesized that in patients with completely resected lung cancer, surveillance with MnDCT, when compared with CXR, leads to earlier detection and a higher rate of treatment of new or recurrent lung cancer. METHODS: After lung cancer resection, patients prospectively were enrolled for surveillance with MnDCT and CXR at 3, 6, 12, 18, 24, 36, 48, and 60 months. Images were interpreted by different blinded radiologists. When new or recurrent cancer was suspected, standard-dose CT and/or a tissue biopsy were performed for confirmation. RESULTS: Between 2007 and 2012, 271 patients were included and 1137 pairs of CXR and MnDCT were analyzed. MnDCT was more sensitive (94% vs 21%; P < .0001) and had a higher negative predictive value (99% vs 96%; P = .007) than CXR for the diagnosis of new or recurrent lung cancer. The prevalence of new or recurrent lung cancer was 23.2% (63 of 271), of whom 78% (49 of 63) had asymptomatic disease. The majority of asymptomatic patients (75%; 37 of 49) were treated with curative intent and had a median survival of 69 months. The remainder of patients received palliative treatment (24%; 12 of 49) and had a median survival of 25 months (P < .0001). CONCLUSIONS: After curative resection of lung cancer, MnDCT is superior to CXR for the detection of new or recurrent lung cancer. The majority of new or recurrent cancer was detected by MnDCT at an asymptomatic phase, allowing for curative treatment, leading to a long survival.
