Lung-only metastatic pancreatic cancer: Differences in patients 'characteristics, molecular profile and survival.

[BACKGROUND] A better prognosis is suggested for lung-only metastases patients with pancreatic ductal adenocarcinoma (PDAC), yet biological/clinical underpinnings of organotropism in PDAC remain unclear. Study objective was to compare PDAC patients depending on their metastatic site with a special focus on "lung-only" metastases patients.

[METHODS] A retrospective analysis included all patients with metastatic PDAC between 2010 and 2022 in an academic-center. Lung-only patients were defined as patients with only lung metastases at diagnosis of metastases.

[RESULTS] Among 1012 patients, 109 (11 %) presented lung-only metastases, 506 patients (50 %) liver-only, 94 (9 %) peritoneal-only and 303 (30 %) other or multiple sites. Compared with others, lung-only patients were more frequently female (63 % vs. 46 %), older at metastatic diagnosis (median 66 vs. 63 years, p = 0.01), and less likely to have synchronous metastases (42 % vs. 69 %, p < 0.001). ctDNA detection was lower in the lung-only group with less KRAS mutations and TP53 mutations detected with liquid biopsy (but no difference was observed using tumor tissue). Median OS was higher in the lung-only group with 28.7 months (95 %CI [23.3-38.6]) vs 13.5 months (95 %CI [12.4-14.6]) for liver-only group, 11.5 months (95 %CI [9.6-16.9]) for peritoneal-only group and 11.3 months (95 %CI [10.0-13.8]) for other patients (p < 0.0001). Among lung-only patients, local treatments (n = 15) had a positive prognostic impact.

[CONCLUSIONS] Patients with lung-only metastases had a better OS than others, were more often women, and harbored less KRAS mutations. Our results argue in favor of PDAC with specific characteristics, especially a better prognosis, possibly further enhanced by the possibility to perform local treatments, and less detection of ctDNA.