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Published on: July 25, 2011
[Microscopic extensions of head and neck squamous cell carcinomas: impact for clinical target volume definition]
Purpose:
To assess microscopic extensions of head and neck squamous cell carcinomas aiming at a proposal for target volumes of radiation therapy.
Materials And Methods:
Surgical specimens were prospectively analysed macroscopically and microscopically. Tumour borders were identified per macroscopic visual examination and inked on stained slides. Then microscopic implants (perineural or lymphatic involvement, or in situ carcinomas) were looked for with an optic microscope in the macroscopic healthy tissue surrounding the tumour. The maximal length from tumour border was correlated with the maximal length of macroscopically healthy tissues assessable.
Results:
Twenty-one specimens were analysed and 12 were locally advanced tumours. Mean and median maximal microscopic extensions were 2.9 and 1.0mm (0-15mm), respectively. The 90th and 95th percentiles were 5 and 11mm, respectively. The ratio between healthy tissue length and maximal microscopic tumour extension was 10%. No correlation was found with tumour grade or volume.
Conclusion:
The presence of microscopic tumour was unlikely after 5mm from macroscopic tumour (≤5% of patients in this series) but should be assessed along with other histoclinical factors and particularities of tumour behaviour by anatomic site. A rigorous terminology should authorize a relevant appreciation of local risk of recurrence, particularly in adjuvant setting or for clinical target volume definition. Larger and more homogenous confirmatory series are needed.
Insights
Microscopic tumor extensions in head and neck squamous cell carcinoma rarely exceed 5mm. This finding aids in defining radiation therapy target volumes for improved patient outcomes.
Area of Science:
- Oncology
- Surgical Pathology
Context:
- Head and neck squamous cell carcinomas (HNSCC) present challenges in determining accurate tumor margins.
- Microscopic tumor infiltration beyond macroscopic borders is critical for treatment planning.
Purpose:
- To evaluate microscopic tumor extensions in HNSCC.
- To propose guidelines for radiation therapy target volumes based on these extensions.
Summary:
- Analysis of 21 HNSCC specimens revealed mean and median microscopic extensions of 2.9mm and 1.0mm, respectively.
- The 95th percentile for microscopic extension was 11mm, with 5mm encompassing 95% of cases.
- No correlation was observed between microscopic extension and tumor grade or volume.
Impact:
- Findings suggest that microscopic tumor spread is unlikely beyond 5mm in most HNSCC cases.
- This research informs the definition of clinical target volumes for radiation therapy.
- Standardized terminology is recommended for precise local recurrence risk assessment.
