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Superficial BCC- Why it is important to measure depth

Sasi Attili


I have seen pathology colleagues in my career who scoff at the idea of Dermatologists asking for depth measurements for BCC's. There is a valid reason for this as thin (<1mm) lesions are more likely to respond to non-surgical treatments like Imiquimod and PDT, than thicker ones.

This recent paper below in the BJD, however suggests that the cut off should be <0.4mm. However we do need larger studies and re-think how we define superficial BCC. The authors raise very interesting points regarding defining sBCC- well worth a read.

[size=3][b]Thickness of superficial basal cell carcinoma (sBCC) predicts imiquimod efficacy: a proposal for a thickness-based definition of sBCC.[/b]

[color=#000000][font=arial, helvetica, clean, sans-serif][url="http://www.ncbi.nlm.nih.gov/pubmed?term=McKay%20KM%5BAuthor%5D&cauthor=true&cauthor_uid=23627639"]McKay KM[/url], [url="http://www.ncbi.nlm.nih.gov/pubmed?term=Sambrano%20BL%5BAuthor%5D&cauthor=true&cauthor_uid=23627639"]Sambrano BL[/url], [url="http://www.ncbi.nlm.nih.gov/pubmed?term=Fox%20PS%5BAuthor%5D&cauthor=true&cauthor_uid=23627639"]Fox PS[/url], [url="http://www.ncbi.nlm.nih.gov/pubmed?term=Bassett%20RL%5BAuthor%5D&cauthor=true&cauthor_uid=23627639"]Bassett RL[/url], [url="http://www.ncbi.nlm.nih.gov/pubmed?term=Chon%20S%5BAuthor%5D&cauthor=true&cauthor_uid=23627639"]Chon S[/url], [url="http://www.ncbi.nlm.nih.gov/pubmed?term=Prieto%20VG%5BAuthor%5D&cauthor=true&cauthor_uid=23627639"]Prieto VG[/url].[/font][/color]

[color=#000000][font=arial, helvetica, clean, sans-serif][b] Source[/b]

Departments of Dermatology and Pathology, The University of Alabama at Birmingham, Birmingham, AL, U.S.A.[/font][/color]

[color=#000000][font=arial, helvetica, clean, sans-serif][b] Abstract[/b]


Basal cell carcinoma (BCC) is the most common malignancy in the white population. It is an important driver of healthcare costs and causes significant morbidity. Topical imiquimod is a good noninvasive treatment alternative for surgical excision in superficial BCC (sBCC). However, there are currently no uniform histological definitions of sBCC. A definition based on tumour thickness might be a good alternative.

To determine whether tumour thickness in sBCC is a predictor of treatment failure.
[b] METHODS:[/b]

We retrospectively examined 127 histological biopsy specimens of sBCC treated primarily with imiquimod five times a week for 6 weeks. Mean follow-up was 34 months (range 3-91). Recurrence was evaluated clinically with histological verification.
[b] RESULTS:[/b]

Among nonrecurrent cases the median tumour thickness was 0·26 mm (range 0·09-0·61), while for recurrent cases the median tumour thickness was 0·57 mm (range 0·41-1·41, P < 0·0001). Among lesions ≤ 0·40 mm in thickness, none recurred, whereas for lesions > 0·40 mm the recurrence rate was 58% (P < 0·0001).

We recommend the use of tumour thickness to define the superficial pattern in pathology reports for BCC as this can help to determine treatment response of sBCC to imiquimod.[/font][/color][/size]


Recommended Comments

Good question Vivek. I was used to using 2mm (no scientific evidence behind it). But laterly have come down to 1mm. Maybe need to come down further based on this study.
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Robledo F. Rocha


The AJCC Cancer Staging doesn’t deem importance to depth in basal cell carcinoma, but only in squamous cell carcinoma, using as cutoff point 2 mm of tumor thickness and other high-risk features to stratify the prognosis correlated with an increased risk of metastases, not with response to non-surgical treatments.
I think there’s a gap waiting to be filled because the preference for drug-based treatments for cutaneous carcinomas in detriment of the surgical ones is a reality whose chance of success must have parameters to be evaluated. Thus, the best therapeutic proposal may be chosen based on scientifically valid data.
Thanks for the excellent blog.
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Dr. Richard Carr


We use 1mm as a histological cut-off as this was the depth the clinical colleagues were prepared to consider PDT etc. We don't give the actual depth though (I refused). I have not read the paper but certainly wonder how cutting levels might affect the thickness - was this studied?
Thanks Sasi
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