This study analysed the characteristics of three different processes of intrathoracic disseminated lung cancer.
Patients of postoperative recurrent M1a(r-M1a), intrathoracic accidental invisible M1a(s-M1a) and clinical diagnosis of M1a(c-M1a) and received TKI were retrospectively collected.
r-M1a: From 2005.01 to 2009.12, postoperative recurrent M1a of Guangdong Lung Cancer Institute was 59 (2.4%), postoperative pathological stage of I/II/III was 30/8/21, respectively. The average progress to M1a was 25.0 months. From the progression of M1a, median OS (OS1) was 34.0 months (95% CI, 26.4-41.6). OS1 was similar to stage IIB (31.0 months) of the 7th edition of the TNM classification of malignant tumors. s-M1a: From 2007.08 to 2013.06, consecutive lung cancer patients receiving thoracotomies at Guangdong Lung Cancer Institute were retrospectively analyzed. Fifty-eight patients (3.9%) receiving incomplete resections (R1/R2) were enrolled, including 38 patients with local residual cancer (IIIB) and 20 patients with disseminated pM1a (IV). Median OS was 15.0 and 45.0 months, respectively (P = 0.001). Cox regression analysis revealed that group was the only independent prognostic factor (P = 0.044) for OS. c-M1a: From 2007.01 to 2012.12, 388 consecutive lung cancer patients receiving TKI at our institute were analyzed. Finally, 230 (59.3%) cases were enrolled. Median PFS for Iressa group (119) and Erlotinib group (111) was both 9.0 months. Median PFS for 76 cases was longer than 1 year, including 27 cases of M1a (35.5%). Median PFS for 16 cases was longer than 2 years, including 6 cases of M1a (37.5%). Three modes of TKI resistance were found as follows: 130 patients with dramatic progression, 42 with gradual progression, and 55 with local progression. Median OS was 17.1, 39.4 and 23.1 months, respectively (P < 0.001). However, M1a proportion of these three groups was 11/130, 13/42 and 3/55 (P < 0.001).
r-M1a, s-M1a and c-M1a were three different processes of intrathoracic disseminated lung cancer with similar clinical and pathological features. The progression of M1a was relatively slow in advanced lung cancer and it might be a distinct lung cancer subtype with a favorable prognosis.
Clinical trial identification
All authors have declared no conflicts of interest.