Pathology of advanced buccal mucosa cancer involving masticator space (T4b).

BACKGROUND: Buccal mucosa cancer involving masticator space is classified as very advanced local disease (T4b). The local recurrence rate is very high due to poor understanding of the extent of tumor spread in masticator space and technically difficult surgical clearance. The objective of this study is to understand the extent of tumor spread in masticator space to form basis for appropriate surgical resection. MATERIALS AND METHODS: All consecutive patients with T4b-buccal cancer underwent compartment resection, with complete anatomical removal of involved soft-tissue structures. Specimens were systematically studied to understand the extent of invasion of various structures. The findings of clinical history, imaging and pathologic evaluation were compared and the results were evaluated. RESULTS: A total of 45 patients with advanced buccal cancer (T4b) were included in this study. The skin, mandible and lymph nodes were involved in 30, 24 and 17 cases respectively. The pterygoid muscles were involved in 34 cases (medial-pterygoid in 12 and both pterygoids in 22 cases) and masseter-muscle in 32 cases. Average distance for soft-tissue margins after compartment surgery was 2 cm and the margins were positive in 3 cases. The group with involvement of medial pterygoid muscle had safest margin with compartment surgery while it was also possible to achieve negative margins for group involving lateral pterygoid muscle and plates.The involvement of pterygomaxillary fissure was area of concern and margin was positive in 2 cases with one patient developing local recurrence with intracranial extension. At 21 months median follow-up (13-35 months), 38 patients were alive without disease while two developed local recurrence at the skull base. CONCLUSIONS: T4b buccal cancers have significant soft-tissue involvement in the masticator space. En bloc removal of all soft-tissues in masticator space is advocated to remove tumor contained within space. The compartment surgery provides an opportunity to achieve negative margins for cancers actually contained within masticator space.It is inappropriate to club all patients with masticator space involvement in one group.

Prevalence of KRAS mutations in metastatic colorectal cancer: A retrospective observational study from India.

BACKGROUND: One of the genetic alterations implicated in tumor progression in colorectal cancers (CRCs) are abnormalities in Kristen Rat Sarcoma (KRAS) gene. Evaluation of KRAS mutation status is an important prognostic factor and has predictive value in deciding first line therapy based on monoclonal antibodies such as Cetuximab and Panitumumab in metastatic CRCs. MATERIALS AND METHODS: In this retrospective study, we analyzed 7 different somatic mutations in Exon 2 of KRAS gene in 299 unselected incidental CRC patients who visited the hospital for clinical management during the period 2009-2013. Most of the tumors were primarily originating from colon and rectum; nevertheless, there were a few from rectosigmoid, sigmoid, ceacum and anal canal in the study group. Genomic DNA extracted from paraffin embedded tumor tissues was screened for 7 point mutations located in Codons 12 and 13 of KRAS gene, using Scorpions amplified refractory mutation system real time polymerase chain reaction technology. Statistical analysis was performed to assess bivariate relationship between different variables that includes: mutation status, mutation type, tumor location, tumor morphology, age and sex. RESULTS: Prevalence of mutation in Codons 12 and 13 was 42.8% in the study group. Well-differentiated tumors had significantly more mutation positivity than moderately and poorly differentiated tumors (P = 0.001). 92% of the mutations were from Codon 12 and 8% in Codon 13. Glycine to Arginine was relatively more common in rectosigmoid followed by ceacum, while Glycine to Alanine mutation was relatively more prevalent in sigmoid, followed by rectum and rectosigmoid. CONCLUSION: The results suggest a prevalence of KRAS mutation at 42.8% in Indian population indicating that this testing is very crucial for targeted therapy management in metastatic CRC in India. Further analysis on mutation status of other homologues such as NRAS and downstream partner, v-raf murine sarcoma viral oncogene homolog B1, would add value to understanding the role of anti-epidermal growth factor receptor therapy in CRC management.

A retrospective evaluation of submandibular gland involvement in oral cavity cancers: a case for gland preservation.

The key factor mitigating against prognosis in head and neck cancer is nodal metastasis and its management. Neck dissection has been known to play an integral part in this type of cancer management. Submandibular gland preservation during neck dissection and post radiotherapy, have been known to improve subjective symptoms of xerostomia. The authors retrospectively surveyed the involvement of submandibular gland involvement in oral cancer with a view to confirm oncologic safety of submandibular gland preservation, as a first step in a quest to manage radiation induced xerostomia by submandibular gland transfer. The medical and pathological records of oral cancer patients who underwent surgical treatment at the authors' centre were reviewed retrospectively. 194 patients were included in the study. 229 submandibular glands were excised from the same number of neck dissections. 3 (1.3%) submandibular glands were involved with malignancies microscopically. The mode of involvement was by direct infiltration. In conclusion, no metastasis to submandibular gland was observed. This may suggest the oncologic safety of submandibular gland preservation and transfer.