Depth of Invasion in Oral Cavity Squamous Cell Carcinomas: A Radiologist's Perspective

[摘要] Oral cavity cancers are the third-most common form of cancer in India, with an increasing trend. Resectable oral squamous cell carcinoma (SCCa) is primarily treated with surgery with the addition of postoperative radiotherapy (PORT) with or without chemotherapy in the presence of adverse pathological features. Cervical lymph nodal metastasis is an important negative prognostic factor of oral cavity cancer. In patients with oral cavity SCCa without clinically detectable lymph nodal metastases (N0 neck), the treatment of the neck is principally dependent on the potential risk of developing occult nodal metastases. If this potential risk is low, observation of the neck is the recommended line of management. However, if the potential risk is high, an elective neck dissection (END) should be performed. Ideally, the management of patients with cT1N0 SCCa must strike a balance between possible surgical morbidity and optimal oncological outcomes. To prevent unnecessary ENDs, reliable preoperative biomarkers and predictors need to be developed, to accurately identify N0 necks and reduce the number of unnecessary ENDs. Depth of invasion (DOI) and tumor thickness are two such important predictors of lymph nodal metastases. What is the difference between DOI and Tumor thickness? DOI is defined as the distance from the reconstructed mucosal surface or the basement membrane to the deepest level of invasion [Figure 1a-c]. Tumor thickness is defined as the distance between the top of the tumor to the deepest level of invasion. The two terminologies are not the same or interchangeable, and, it is believed by some authors that tumor thickness underestimates the aggressive potential of the tumor.[2,3] Tumor thickness may be larger than DOI in a proliferative or exophytic tumor, and, lower than DOI in an ulcerative or endophytic tumor [Figure 1d-f].

[学科分类] 皮肤病学