Sharing our research on melanoma surgery
21 March 2018
The global surgical oncology community is in Chicago this week attending the prestigious Society of Surgical Oncology Annual Cancer Symposium. More than 1,800 health care professionals will be attending the conference, including a number of surgeons and researchers from Melanoma Institute Australia who will be presenting their research findings.
Prof John Thompson will be sharing his knowledge on using ultrasound as a surveillance technique for regional lymph nodes in melanoma patients.
Although ultrasound is not sensitive or specific enough to accurately detect metastases in sentinel lymph nodes, it can detect some metastases much earlier than clinical examination in regional lymph nodes for patients who have had a positive sentinel lymph node biopsy but not a completion lymph node clearance. This can be an effective, non-invasive way to monitor for disease progression in the lymph nodes.
MIA was part of an international research team that published the results of a practice-changing study last year, the second Multicenter Selective Lymphadenectomy Trial (MSLT-II). This found no survival benefit in patients who had an immediate completion lymph node dissection following a positive sentinel lymph node biopsy compared to patients who were closely monitored with regular ultrasound assessment of their residual lymph nodes to detect disease progression. This finding will reduce the need for major surgery for many patients.
Prof Thompson will be discussing how ultrasound is likely to become a routine practice when monitoring patients with melanoma for disease progression.
Results from the MSLT-II trial are changing the treatment landscape for patients with Stage III melanoma. Dr Isaacs’ research during her time as the 2016 Poche Surgical Fellow at MIA followed melanoma patients who did not undergo a completion lymph node dissection after a biopsy revealed there were metastases in the sentinel lymph node. In the median 7 years that the patients were followed, she found that approximately a third of patients had no further melanoma, one third had a recurrence in their regional lymph nodes and one third died of their melanoma. The size of the metastasis in the sentinel lymph node, the age of the patient, the thickness of the primary melanoma and the size of the metastasis in the sentinel lymph node all predicted survival outcomes.
MIA’s 2017 Poche Surgical Fellow, Dr Erica Friedman, will be sharing her research findings on the correlation between surgical and histological margins in melanoma. Wide excision during surgery is the mainstay of treatment for localised primary melanoma, and if the margins are too narrow when viewed by a pathologist, the risk of local recurrence increases.
Dr Friedman and her colleagues set out to understand exactly how much the tumour sample shrinks when it’s taken from the patients and is fixed in formalin when viewed by the pathologist. Her research concluded that there is a 14% correction factor which accounts for fixation and shrinkage of the tumour specimen.
Perhaps more relevant to surgeons, she found that the correlation between a measured surgical margin and the margin assessed by the pathologist is highly variable. This suggests that it is difficult to predict the microscopic clearance margin from the planned surgical excision and raises the important question of whether clinical practice guidelines should be changed to require satisfactory microscopic clearance margins rather than simply specifying surgical margins measured before excision.
Patients with a primary melanoma below the knee may have a sentinel node at the back of the knee joint, known as the popliteal fossa. There is little known about sentinel nodes in this area, and so MIA’s visiting research student, Amanda Nijhuis, investigated the clinical relevance of these nodes in patients with a primary melanoma below the knee.
Her research found the melanoma below the knee only infrequently drains to the sentinel nodes in the popliteal fossa and these nodes can be challenging to surgically remove. 16% of patients in the study had a positive popliteal sentinel node and in 10% it was the only positive sentinel node. Patients with a negative popliteal sentinel node had a better survival chance. Removal of these sentinel nodes provides important staging information that may guide further management.