How Biden should have dealt with his skin cancer
There is a new research tool that could have been informative for assessing President Biden’s cancerous lesion.
The White House physician said that a small cancerous lesion was removed on Feb 16th from President Biden’s chest, and that all cancerous tissue had been removed.
The President’s medical team took a biopsy, a small sample of the excised tissue, for evaluation, and determined that it was basal cell carcinoma. Basal cell carcinoma is the most common type of cancer in the world, reportedly affecting one in five people in the US:
According to President Biden’s physician Kevin C. O’Connor, basal cell carcinoma doesn’t spread (metastasize) the way melanoma does. Indeed, basal cell carcinoma is often localized to the primary site at which is was detected:
However, basal cell carcinoma is considered high risk if any of several features are detected. Since the lesion was described as localized, we can conclude that most likely none of these features were present.
- A lesion larger than 2 cm on the trunk or extremities — since the lesion was on the President’s chest, we can presume it was less than 2 cm in diameter.
- A recurrent tumor — presumably it had never occurred in this site before.
- A poorly defined tumor — presumably it had a well defined shape.
- Invasion into the area around a nerve — presumbly the lesion was not adjacent to a nerve.
Most likely, the biopsy was analyzed by one or more types of microscopy to determine the stage and aggressiveness of the cancer.
Assuming to the be the case, the lesion would have been removed with at least 4 mm margins, and then the region about the removed lesion checked for any remaining cancerous tissue.
https://www-sciencedirect-com.ezproxy.cul.columbia.edu/science/article/pii/S0733863522000572#bib29
From the statement of the White House physician, we can conclude the margins were free of cancerous tissue.
However, could a small number of pre-malignant or malignant cells have invaded the surrounding tissue that would not readily be detected by microscopy?
New advances in single cell RNA sequencing allow for the analysis of the profile of expressed genes in single cells. Although this is currently a few thousand dollars to run, and couldn’t be routinely used for diagnosis, for the President of the United States, it could be valuable information.
Performing single cell RNA sequencing on the lesion and surrounding tissue would allow for an assessment of the makeup of tumor cells within the lesion, as well as in the surrounding tissue. This would allow for a better assessment of any invasion into the surrounding tissue, and assignment of the heterogeneity and subtype of the cancer that was removed.
Single cell RNA sequencing is pretty standard in research labs, and I wonder why this isn’t yet used as a diagnostic tool in assessing skin cancer. Perhaps in time this will be adopted in more difficult diagnostic cases.
