With use of validated risk factors, the investigators applied a long list of risk factors to 2,000 tumors to see which risk factors, taken individually, were really contributing to poor outcomes. Eventually, four risk factors that made the most difference were identified: size greater than 2 cm, poor tumor differentiation, perineural invasion greater than 0.1 mm in diameter, and tumor invasion beyond subcutaneous fat. “I really want to highlight the size portion of those risk factors,” said Dr. Patel. “Something I’d like you to do in your clinical practice is to measure and document the size of the lesion. … That really, clearly helps” with risk prognostication.
These four factors were then used to break out a T2a stage for tumors with one risk factor and a T2b stage for tumors with two or three risk factors. Tumors with no risk factors are stage T1, and those with all four risk factors are stage T3. In situ SCC is T0.
Applying this new staging system to a 2,000-patient cohort with SCC yielded clear separation in outcomes including recurrence, nodal metastasis, disease-specific death, and overall survival between patients with the T2a and T2b tumors (P less than .001 for all;).
While AJCC 8 is “significantly better” than AJCC 7 in its incorporation of meaningful risk factors into the SCC staging system, “it still underperforms in comparison” with the BWH staging system using the 2000 patient cohort, he said. Recent work has shown the BWH classification system to have superior specificity and positive predictive value in detecting nodal metastasis and disease-specific death in higher-grade tumors. But both BWH and AJCC 8 need further refinement.
“So what are the staging pearls to take home?” Dr. Patel asked. “First, utilize a staging system.” “Staging of SCC utilizing should be done routinely. Most data seems to suggest that the BWH system appears to outperform AJCC 8, and it is what we currently use routinely at GW,” he said.
Patients who are T1 by BWH criteria, with no risk factors, are at low or even no risk, he noted. He pointed out that of the nearly 1,400 patients who met T1 criteria, there were just eight local recurrences, one nodal metastasis, and no distant metastases or deaths. Knowing this should guide physicians on a treatment path that will reduce costs and provide patients with peace of mind, he said.
In the BWH schema, T2a patients fared almost as well, with a 2% risk of nodal metastasis and an overall 1% risk of disease-specific death. “T2a disease is low risk, in my mind. Most of these patients will go on to do well,” he said.
By contrast, “there may be a number of tumors that you are missing” that are candidates for close follow-up if the BWH criteria are not being used, said Dr. Patel. These are the T2b tumors. “For those patients, we want to aggressively follow them and think about a more aggressive management plan.”
The bottom line is that BWH T2b and T3 tumors are both high risk, and management needs to acknowledge this, he said. The current protocol in our cutaneous oncology program includes using routine radiologic nodal staging in patients with BWH stage 2b and above SCCs and considering sentinel lymph node biopsy for certain individuals.
For patients with BWH T2b and T3 tumors, dermatologists should give consideration to tertiary care or cancer center referrals so they have access to the full spectrum of diagnostic and therapeutic modalities and the opportunity to participate in clinical trials, Dr. Patel said.
Dr. Patel reported that he is a speaker for Regeneron/Sanofi and a cofounder of the Skin Cancer Outcomes (SCOUT) consortium.
This article was updated 2/9/2019