The indolent nature of pulmonary metastases from ductal adenocarcinoma of the pancreas

Abstract

Background and objectives: The natural history of pulmonary metastases from pancreatic ductal adenocarcinoma (PDAC) is not well studied. Limited evidence suggests patients with isolated pulmonary metastases from PDAC follow a more benign clinical course than those with other sites of metastases.

Methods: We performed a retrospective review of all patients with pulmonary metastases from PDAC from 2000 to 2010 and analyzed survival utilizing the Kaplan-Meier method based upon location of first metastasis (lung first, intra-abdominal first, or synchronous intra-abdominal and lung metastases).

Results: Median survival among subjects with lung as the only site of metastases was significantly longer than those with other metastatic patterns. In subjects that had undergone resection of their PDAC, survival in those with lung as a first site of recurrence remained significantly longer than those with abdominal first or synchronous intra-abdominal and lung recurrence. Among resected patients that developed lung only recurrence, survival was significantly prolonged (67.5 months) in those who underwent surgical resection/stereotactic radiosurgery compared to chemotherapy (33.8 months) or observation (29.9 months) for treatment of lung recurrence.

Conclusion: Patients with isolated pulmonary recurrence from PDAC may realize a survival benefit from surgical intervention or stereotactic radiosurgery compared to chemotherapy or observation for treatment of lung recurrence.

Keywords: lung metastases; pancreatic ductal adenocarcinoma; pulmonary metastases.

Figure 1. Median survival in all patients with pulmonary metastases from PDAC grouped by site of first metastases

Among those with lung as a first and only site of metastases, median survival was 23.1 months compared to 16.5 months for those with lung first but not only metastases, 12.9 months for those with abdominal metastases before lung metastases, and 7.3 months for those with synchronous intra-abdominal and lung metastases. Using patients with lung only metastases as a reference for comparison, the hazard ratios of death are 1.5 (95% C.I. 0.94-2.45, p=0.091) for patients with lung first but not only metastases, 2.2 (95% C.I. 1.43-3.23, p<0.0001) for patients with abdominal first metastases, and 3.3 (95% C.I. 2.2-5.1, p<0.0001) for patients with synchronous abdominal and lung metastases.

Figure 2. Median survival in patients who underwent resection of primary PDAC

Among those patients who underwent resection of their primary PDAC, the median survival of those with lung as a first recurrence was 35.6 months compared to 23.8 months among those with abdominal first or synchronous recurrence (p= 0.003).

Figure 3. Median survival in patients who underwent resection of their primary PDAC and developed lung metastases as a first site of recurrence by treatment strategy

Among those patients who underwent resection of their primary PDAC and developed lung recurrence first, those who underwent surgery or stereotactic radiosurgery had a median survival of 67.5 months (95% C.I. 23.9-) compared to 33.8 months (95% C.I. 23.2-44.9) among those who were treated metastases directed chemotherapy or observation alone (p=0.006).