Salivary gland carcinomas are a rare group of tumors with diverse histologies. This has led to a lack of good quality data on various aspects of the disease. As a result, there were limited options for treating them. But, with the advent of targeted therapies, a gamut of options has opened up for the same.
This is a retrospective study done at a tertiary care oncology center in a low -middle-income country over a period of last 3.5 years. All patients aged 18 and above presenting with metastatic or unresectable locally advanced salivary gland tumors were included.
Out of 24 such patients, male predominance (75%) was noted. 21(88%) had origin from parotid and 3(12%) from submandibular gland. 11(46%) of them were salivary duct carcinoma, 7 (29%) were adenoid cystic carcinoma and 6(25%) were mucoepidermoid carcinoma. Among salivary duct carcinoma, androgen receptor (AR) and HER 2 expression were 89% and 55 % respectively. In mucoepidermoid carcinoma, AR and HER 2 expressions were 16 and 20% respectively while for adenoid cystic carcinoma, AR and Her2 expression was 0%. In 1 patient with SDC, PIK3CA exon 20 mutations with HRAS and TP 53 mutations were detected. Lung was the site of metastasis in 79% of cases followed by bone in 26% of cases. 10(42%) patients received initial chemotherapy out of which 3 (30%) were also added trastuzumab. 4 (17%) of them were treated initially with anti-androgen therapy. 7 patients have gone to second-line therapy of which 2 have received anti-androgen therapy.
Salivary duct carcinomas of the parotid gland are the commonest advanced salivary gland tumors with significantly higher positivity of AR and HER 2 which can be targeted. Further NGS-based testing should be done to bring out the molecular alterations in other subtypes.
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