The Prognosis and Natural History of In-Transit Melanoma Metastases at a High-Volume Centre

Burden of Care for Patients With In-Transit Melanoma

INTRODUCTION

Patient burden of cancer care can be significant, especially for cancers like melanoma where patients are living longer, even with advanced disease. The purpose of this study is to compare the burden of treatment of melanoma patients with in-transit metastases (ITM). There are multiple treatment options for ITM, but no standard due to lack of large cohort comparative studies; thus, the anticipated burden of care may influence therapy choice.

METHODS

Included patients had in-transit melanoma without distant metastasis and were managed at our institution from July 1, 2015 through December 31, 2020 using a combination of surgery, systemic, intralesional, and radiation therapy. We compared treatment burden, (number of treatments, clinic visits, inpatient hospital days, and distance traveled) and response rates using Kruskal-Wallis and chi-squared tests. Recurrence-free survival and estimated charges were exploratory endpoints.

RESULTS

There were 42 patients who met the inclusion criteria. As initial treatment, patients had surgery (n = 20), surgery with adjuvant (n = 6), systemic (n = 9), and intralesional therapy (n = 2). Surgery had the lowest treatment burden (median of 1 treatment, 3 clinic visits, and 0 inpatient days) while surgery with adjuvant systemic therapy had the highest burden (median of 13 treatments, 12 clinic visits, and 0 inpatient days). Systemic, intralesional, and radiation therapy were used more often for recurrent ITM. Travel distance (P = 0.88) and response rates did not statistically differ between the four options for first line therapy (P = 0.99). At a median follow-up time of 8.8 mo, 22 (52%) of the cohort required more than 1 therapy to manage recurrent or progressive disease and 14 (33%) progressed to distant disease.

CONCLUSIONS

Treatment of in-transit melanoma is associated with high burden of care and often requires multiple therapies, even with maximally effective first treatment choice. Factors evaluated in this study may be used to set expectations of treatment course for newly diagnosed patients and may aid in patients' decisions on therapy selection.

PET/CT variants and pitfalls in malignant melanoma

¹⁸F-FDG PET/CT plays an increasingly pivotal role in the staging and post-treatment monitoring of high-risk melanoma patients, augmented by the introduction of therapies, including tyrosine kinase inhibitors (TKI) and immune checkpoint inhibitors (ICIs), that have novel modes of action that challenge conventional response assessment. Simultaneously, technological advances have been regularly released, including advanced reconstruction algorithms, digital PET and motion correction, which have allowed the PET community to detect ever-smaller cancer lesions, improving diagnostic performance in the context of indications previously viewed as limitations, such as detection of in-transit disease and confirmation of the nature of small pulmonary metastases apparent on CT.This review will provide advice regarding melanoma-related PET protocols and will focus on variants encountered during the imaging of melanoma patients. Emphasis will be made on pitfalls related to non-malignant diseases and treatment-related findings that may confound accurate interpretation unless recognized. The latter include signs of immune activation and immune-related adverse events (irAEs). Technology-related pitfalls are also discussed, since while new PET technologies improve detection of small lesions, these may also induce false-positive cases and require a learning curve to be observed. In these times of the COVID 19 pandemic, cases illustrating lessons learned from COVID 19 or vaccination-related pitfalls will also be described.