Clinical implications of repeat tumor biopsy (RTB) in patients (pts) with advanced lung cancer (LC): The Cleveland Clinic (CC) experience.

Background:  RTB at disease progression (PD) is increasingly used to profile tumor biomarkers and identify drug resistance mechanisms. However, information on safety and clinical consensus on the use of RTB remain lacking.  Methods:  The aim of this study is to review RTB patterns and safety in LC pts at CC and impact on treatment (Rx) decisions. Pts who were diagnosed and underwent RTB for suspected LC PD between 2007 and 2013 were studied. Statistical analysis is primarily descriptive.  Results:  The study involved 184 (56% male) pts. Median age at diagnosis was 65Y (21-87). 100 (54%) were treated initially with single modality (Surgery = 41; Chemo = 33; Radiation = 17; targeted therapy = 9) and 83 (45%) with multimodality Rx (2-modality = 57, 3-modality = 26), 1 (1%) unknown. # Of RTB per patient: 1 in 66.3% (n = 122), 2 in 20.1% (n = 37), 3 in 11.4% (n = 21), and 4 in 2.2% (n = 4). The most common procedure at 1st RTB was bronchoscopy (44.6%, n = 82), followed by CT guided biopsy (bx) (20.7 %, n = 38), surgery (10.3%, n = 19), excision bx (8.2%, n = 15), fine needle aspiration of skin & lymph node (LN) (7.6%, n = 14), ultrasound guided bx (5.9%, n = 11) & others (2.7%, n = 5). Lung was the most commonly re-biopsied site (46%) followed by LN (15%). Complications occurred in 13 of 181 (7.2%) pts at 1st RTB (data missing in 3 pts), 3 of 61 (4.9%) at 2nd RTB, 1 of 25(4%) at 3rd RTB, and 0 of 4 (0%) at 4th RTB. The 17 (6.2%) complications are shown in the table below. Histologic change was seen in 13 cases, including adeno-to-squamous carcinoma (at erlotinib resistance) and vice-versa, and non-small cell to small cell histology. The T790M-EGFR mutation was noted in 6 cases, the PIK3CA mutation in 1, and a change in ALK status in 3. Medical decision making was impacted in 16% of cases.  Conclusions:  RTB can be safely performed using minimally invasive techniques and can benefit LC Rx decision making.