Background Agreement on the utility of imaging follow-up in patients with high-risk melanoma is lacking. A UK consensus statement recommends a surveillance schedule of CT or positron-emission tomography-CT and MRI brain (every 6 months for 3 years, then annually in years 4 and 5) as well as clinical examination for high-risk resected Stages II and III cutaneous melanoma. Our aim was to assess patterns of relapse and whether imaging surveillance could be of clinical benefit. Patients and methods A retrospective study of patients enrolled between July 2013 and June 2015 from three UK tertiary cancer centres followed-up according to this protocol was undertaken. We evaluated time-to-recurrence (TTR), recurrence-free survival (RFS), method of detection and characteristics of recurrence, treatment received and overall survival (OS). Results A total of 173 patients were included. Most (79%) had treated Stages IIIB and IIIC disease. With a median follow-up of 23.3 months, 82 patients (47%) had relapsed. Median TTR was 10.1 months and median RFS was 21.2 months. The majority of recurrences (66%) were asymptomatic and detected by scheduled surveillance scan. Fifty-six (68%) patients recurred with Stage IV disease, with a median OS of 25.3 months; 26 (31.7%) patients had a locoregional recurrence, median OS not reached (P=0.016). Patients who underwent surgery at recurrence for either Stage III (27%) or IV (18%) disease did not reach their median OS. The median OS for the 33 patients (40%) who received systemic therapy was 12.9 months. Conclusion Imaging appears to reliably detect subclinical disease and identify patients suitable for surgery, conferring favourable outcomes. The short median TTR provides rationale to intensify imaging schedule in the first year of surveillance. The poor OS of patients treated with systemic therapy probably reflects the relatively inferior treatment options during this time and requires further evaluation in the current era.

The early detection of relapse following primary surgery for non-small-cell lung cancer and the characterization of emerging subclones, which seed metastatic sites, might offer new therapeutic approaches for limiting tumour recurrence. The ability to track the evolutionary dynamics of early-stage lung cancer non-invasively in circulating tumour DNA (ctDNA) has not yet been demonstrated. Here we use a tumour-specific phylogenetic approach to profile the ctDNA of the first 100 TRACERx (Tracking Non-Small-Cell Lung Cancer Evolution Through Therapy (Rx)) study participants, including one patient who was also recruited to the PEACE (Posthumous Evaluation of Advanced Cancer Environment) post-mortem study. We identify independent predictors of ctDNA release and analyse the tumour-volume detection limit. Through blinded profiling of postoperative plasma, we observe evidence of adjuvant chemotherapy resistance and identify patients who are very likely to experience recurrence of their lung cancer. Finally, we show that phylogenetic ctDNA profiling tracks the subclonal nature of lung cancer relapse and metastasis, providing a new approach for ctDNA-driven therapeutic studies.