Defining the relevance of surgical margins. Part two: Strategies to improve prediction of recurrence risk.

Due to the complex nature of tumour biology and the integration between host tissues and molecular processes of the tumour cells, a continued reliance on the status of the microscopic cellular margin should not remain our only determinant of the success of a curative-intent surgery for patients with cancer. Based on current evidence, relying on a purely cellular focus to provide a binary indication of treatment success can provide an incomplete interpretation of potential outcome. A more holistic analysis of the cancer margin may be required. If we are to move ahead from our current situation - and allow treatment plans to be more intelligently tailored to meet the requirements of each individual tumour - we need to improve our utilisation of techniques that either improve recognition of residual tumour cells within the surgical field or enable a more comprehensive interrogation of tumour biology that identifies a risk of recurrence. In the second article in this series on defining the relevance of surgical margins, the authors discuss possible alternative strategies for margin assessment and evaluation in the canine and feline cancer patient. These strategies include considering adoption of the residual tumour classification scheme; intra-operative imaging systems including fluorescence-guided surgery, optical coherence tomography and Raman spectroscopy; molecular analysis and whole transcriptome analysis of tissues; and the development of a biologic index (nomogram). These techniques may allow evaluation of individual tumour biology and the status of the resection margin in ways that are different to our current techniques. Ultimately, these techniques seek to better define the risk of tumour recurrence following surgery and provide the surgeon and patient with more confidence in margin assessment.

Evaluating the relevance of surgical margins. Part one: The problems with current methodology.

The goal of cancer surgery is to achieve a "clean" microscopic resection, with no residual tumour remaining in the wound. To achieve that goal, the surgeon typically incorporates a measured buffer of grossly normal tissue about the entire circumference of the tumour. Microscopic analysis of the resection boundaries is then performed to determine if all traces of the tumour have been completely removed. This analysis is thought to provide a surrogate indication as to the likelihood for that tumour to recur after surgery. However, it is recognised that tumour recurrence may not occur even when microscopic evidence of tumour has been identified at the resection margins, and recurrence can also occur when conventional histology has considered the tumour to have been completely removed. The explanations for this dichotomy are numerous and include technical and practical limitations of the processing methodology, and also several surgeon-related and tumour-related reasons. Ultimately, the inability to confidently determine when a tumour has been removed sufficiently to prevent recurrence can impact on the ability to provide owners with confident treatment advice. In this article, the authors describe the challenges with defining the true extent of the tumour margin from the perspective of the surgeon, the pathologist and the tumour. The authors also provide an analysis of why our current efforts to ensure that all traces of the local tumour have been successfully removed may provide an imperfect assessment of the risk of recurrence.

Urinary Pubic Symphysis Fistula Leads to Histopathologic Osteomyelitis in Prostate Cancer Survivors.

OBJECTIVE: To assess the histologic findings in the pubic bone resected during extirpative surgery for urinary pubic symphysis fistula (UPF). The concurrent presence of osteomyelitis and the need for bone resection at time of extirpative surgery for UPF has been debated. We hypothesized that UPF results in histopathologically confirmed osteomyelitis, underscoring the importance of bone resection at the time of surgery. METHODS: An IRB-approved retrospective review of all patients undergoing surgery for UPF from 2012 to 2019 was performed. Demographic data were recorded. A single pathologist performed histopathologic examination of bone tissue in each case. Logistic regression and Fisher exact test were used to assess association of osteomyelitis with clinical factors. RESULTS: We identified 36 patients who underwent major extirpative surgery for UPF with bone pathology available for review. Bone histopathology findings confirmed presence of osteomyelitis in the majority (n = 32, 88.9%). This was characterized as chronic osteomyelitis in 15 (41.7%), acute osteomyelitis only in 1 (2.8%) and combined chronic, and acute osteomyelitis in 16 (44.4%). Osteonecrosis was seen in 11 cases (33.6%). There was no correlation between presence of osteomyelitis and age, timing from radiotherapy to diagnosis of UPF, type of radiotherapy, or history of endoscopic bladder outlet procedures. CONCLUSION: Osteomyelitis is present on histology of the pubic bone resected during surgery for UPF in the majority of cases (88.9%). Osteonecrosis is also common. These findings underscore the critical importance of pubic bone resection at time of UPF surgery to adequately treat the diseased bone.