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SSO meeting spotlights ‘amazing’ progress in surgical oncology
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The Society of Surgical Oncology celebrated its 75th anniversary by meeting from March 25-28 in Houston.
Twenty-two past Society of Surgical Oncology (SSO) presidents, myself included, attended this meeting.
As I look back on my own presidency in 2007-2008, it is amazing to me the progress that has been made in less than a decade with regard to minimally invasive surgery for cancer and the role in which gene profiling contributes to prophylactic surgery for mutation carriers for breast, ovarian and rectal cancers.
It is impossible to summarize many of the exciting and potentially practice-changing presentations in 1,000 words, so my report can be considered the tip of the iceberg. Having said that, I will review three presentations in detail.
Targeted dissection in breast cancer
Nicholas J. Petrelli
The plenary session included a presentation by Caudle and colleagues from The University of Texas MD Anderson Cancer Center, titled “Targeted axillary dissection improves axillary evaluation following neoadjuvant chemotherapy in node-positive patients with breast cancer.”
This study determined whether pathologic changes in clipped lymph nodes reflect nodal response to neoadjuvant chemotherapy, and whether targeted axillary dissection — which includes sentinel lymph node dissection besides selective localization and removal of marked nodes — improves the accuracy of lymph node assessment.
This was a prospective study of patients with axillary metastases identified by ultrasound and confirmed by needle biopsy, with a clip placed in the lymph node.
After neoadjuvant chemotherapy, patients underwent an axillary dissection with radiographic imaging of the axillary contents to identify the clipped lymph node. The pathologic findings of the clipped lymph node were reported separately from other nodes.
Patients who underwent targeted axillary dissection had selective removal of the clipped node using iodine-125 seed localization besides sentinel lymph node dissection before axillary lymph node dissection was performed.
The study included 88 node-positive patients.
The bottom line was that ultrasonic-guided marking of lymph nodes with documented metastatic disease allowed for selective removal of these nodes and improved pathologic evaluation for residual nodal disease. The false-negative rate of sentinel lymph node dissection (11.5%) can be reduced to 2.3% by ensuring removal of the clipped node.
This is an impressive drop in the false-negative rate with a technique that is feasible, safe and allows improved assessment of nodal response after neoadjuvant chemotherapy. The technique also does not require a steep learning curve on the part of the surgeon.
Clinical vs. molecular risk scores
Much has been written in the literature concerning clinical risk scores to prognosticate RFS and OS for patients with resectable colorectal liver metastases.
The fact is, these clinical risk scores have limited accuracy and lack universal agreement and adaptation.
Results from a presentation by Balachandran and colleagues from Memorial Sloan Kettering Cancer Center, titled “An externally validated prognostic multi-gene expression assay for survival in resected colorectal liver metastases,” give hope to a better prognostic tool.
These investigators measured messenger RNA (mRNA) expression using an Illumina microarray on frozen tumors from 96 patients with completely resected colorectal liver metastases at their institution. They created a 20-gene molecular risk score using the supervised principal components method. The investigators then assessed the prognostic ability of chemotherapy, three common clinical risk scores and the molecular risk score for RFS and OS using multivariate Cox regression.
The prognostic ability of the clinical risk scores and the molecular risk score was then assessed on mRNA expression measured on frozen tumor using a Qiagen microarray in an independent external cohort of 119 resected colorectal liver metastases from patients at University Medical Center Utrecht in the Netherlands and the Hôpital Paul-Brousse in France.
Impressively, this study demonstrated that — compared with clinical risk scores — the molecular risk score was more accurate and more broadly applicable and was an independent prognostic biomarker of RFS and OS in this group of patients. The authors reported that this molecular risk score was the first externally validated multigene assay to prognosticate outcomes in resected colorectal liver metastases.
This is the type of research to counter clinical risk scores and, with further study, hopefully will have universal applicability and impact clinical decisions in a positive manner.
A continuing controversy
Discussions — and, to a certain degree, controversy in surgical oncology — continues concerning the nonoperative management of rectal cancer following a complete clinical response to neoadjuvant therapy. However, I would like to emphasize that nonoperative management is not standard of care.
Findings from a presentation by Smith and colleagues from Memorial Sloan Kettering Cancer Center, titled “Organ preservation in rectal cancer patients with clinical complete response after neoadjuvant therapy,” add fuel to the fire.
This was a retrospective review of prospectively collected data during an 8-year period. The study included patients who completed neoadjuvant therapy for stage I to stage III rectal cancers who either achieved a complete clinical response and were treated with nonoperative management or underwent standard total mesorectal excision and achieved a pathologic complete response.
Seventy-three patients underwent nonoperative management after a complete clinical response. From 369 rectal resections performed, 72 (20%) achieved a pathologic complete response and formed the comparison group.
The median follow-up across both groups was 3.3 years, and rectal preservation was achieved in 56 (77%) of the patients treated with nonoperative management. Of 19 nonoperative-managed patients with local re-growth, 19 were salvaged successfully with standard total mesorectal excision or local excision alone. One patient (1.5%) developed a pelvic recurrence after salvage.
The researchers reported no statistically significant differences in the number of distant recurrences between the nonoperative management and the pathologic complete responding groups (17% vs. 9%). There also was no statistically significant difference in 4-year disease-specific survival or OS between the two groups. However, this result may be due to the small patient numbers in the study.
It must be emphasized that this is a highly selected group of patients with a complete clinical response to neoadjuvant treatment. Also, nonoperative management with surgical salvage of local tumor regrowth achieved local control in all patients, with median follow-up of 3.3 years.
These provocative data come from a group of investigators who have long-term experience with these patients. Perhaps, in the near future, a prognostic multigene expression assay as described above for colorectal liver metastases will aid the surgeon in selecting those patients who will not recur following nonoperative management, saving them salvage surgery.
References:
The following were presented at the Society of Surgical Oncology Annual Meeting; March 25-28, 2015; Houston:
Balachandran V, et al. Abstract 4.
Caudle A, et al. Abstract 2.
Smith J, et al. Abstract 8.
For more information:
Nicholas J. Petrelli, MD, is medical director at Helen F. Graham Cancer Center and Research Institute. He also is HemOnc Today’s Associate Editor for Surgical Oncology. He can be reached at Christiana Care Health System, P.O. Box 1668, Wilmington, DE 19899; email: npetrelli@christianacare.org.
Disclosure: Petrelli reports no relevant financial disclosures.