Contemporary Incidence of Synchronous Multiple Primary Lung Cancers and Survival in the Era of Lung Cancer Screening.

OBJECTIVE: Up to 15% of lung cancer patients have multiple suspicious nodules. While some of these nodules may represent metastatic lung cancer, others represent synchronous multiple primary lung cancer (SMPLC). The incidence of SMPLC ranges from 0.8% to 8.4% and appears to be increasing. Inconsistent identification of SMPLC can be detrimental for patients who are misdiagnosed as having intrapulmonary metastasis and not offered stage-based treatment. We sought to identify the contemporary incidence of SMPLC at a tertiary institution. METHODS: From January 2018 to September 2019, patients who underwent lung cancer resection were retrospectively reviewed. Patients with SMPLC were identified using the modified Martini-Melamed criteria. RESULTS: During the 21-month period, 227 patients underwent lung cancer resection. There were 47 patients (20.7%) who had 119 pathologically confirmed SMPLC. Most patients had ipsilateral tumors (n = 24, 51.1%) with at least 1 adenocarcinoma (n = 40, 85.1%). Considering histologic subtyping, 38 (80.9%) had histologically distinct tumors. Overall and cancer-specific survival at 4 years was 86% and 90%, respectively. Only patients with 3 or more SMPLC had poor 4-year overall (P = 0.002) and cancer-specific survival (P = 0.043) compared with those with 2 SMPLC. Patient demographics, histology, tumor location, and highest pathologic staging did not affect survival outcomes. CONCLUSIONS: Using a strict inclusion criterion, the incidence of SMPLC is higher than previously reported. SMPLC patients have favorable survival outcomes, suggesting that they behave like primary lung cancer, not intrapulmonary metastasis. Awareness of SMPLC by thoracic surgeons is critical in optimizing outcomes in this patient population.

Unexpected encounters: high prevalence of synchronous primary lung cancers in a tertiary academic center.

BACKGROUND: Accurate staging of lung cancer is paramount for directing treatment. After an internal audit suggested a higher than expected rate of synchronous multiple primary lung cancers (SMPLC), we have sought to evaluate the prevalence of SMPLC at our single, large academic center. METHODS: From January 2019 to September 2019, patients with non-small cell lung cancer who underwent surgical resection were retrospectively reviewed. Clinical characteristics, pre- and post-op imaging, 30-day morbidity and mortality, as well as pathological findings were reviewed. SMPLCs were defined using modified Martini criteria. RESULTS: Among 83 patients who underwent surgical resection for primary lung cancer with the intention of cure, 17 (20.5%) had pathologically confirmed SMPLC's, 53 (64%) were single primary lung cancers, and 13 (16%) had metastatic lesions from primary lung cancer or extra-thoracic cancers. Mean length of stay was 2 days with no mortalities. Of the SMPLC group, 9 (53%) had previous extra-thoracic neoplasms, compared with 8 (15%) in the single primary group. Four (24%) had a history of resected lung cancers more than 2 years previously, and were participating in lung cancer surveillance programs. CONCLUSIONS: The rate of SMPLC at our institution appears to be considerably higher than traditionally reported. Failure to recognize the high incidence of synchronous primary lung cancers exposes patients to the risks of under treatment and poor outcomes.