Cancer multi-gene panel testing for a patient with a rare type of head and neck cancer

Abstract

We experienced a case in which cancer multi-gene panel testing was performed for a patient with a rare type of head and neck cancer. Namely, salivary duct carcinoma of the parotid gland. In this case, we first detected an overexpression of androgen receptor. CAB therapy was successful. However, the patient's condition subsequently worsened and therefore an extracted cancer tissue specimen was submitted for multi-gene panel testing. An immune checkpoint inhibitor was recommended and administered based on the genetic abnormalities of the neoplastic cells. However, due to the development of an irAE, continuation of the drug became difficult and the outcome was unsatisfactory. The enforcement rate of treatment based on this test is currently low (10%). In addition, we recognized the limitations of enforcement through medical services covered by health insurance. Thus, in order to increase the utilization of this test in order for its usage to spread, governmental approval of this test at the early therapeutic stage is necessary, and the expansion of the indications for the administration of this drug in combination with both insured and non-insured treatments in the current Japanese medical environment is desirable. On the other hand, negative conversion of androgen receptor expression was seen in cancer tissue specimens from this patient whose condition worsened. Therefore, when planning treatment strategies, we must take the intra-tumor heterogeneity which is thought to be an intractable factor into careful consideration.