Is 6 weeks adjuvant radiation necessary.

I was diagnosed with a rare parotid gland cancer called Mammary Analog Secretory Carcinoma. The FNAC said Mucoepidermoid Carcinoma but after tumor removal Histopathology report said Secretory Carcinoma. The total parotidectomy surgery was done successfully with clear margins but a small facial nerve twig was sacrificed because the tumor was going through it. Most of the facial movement is functioning well. The pathology report says T3N0 tumor with no lymph node involvement but some Perineural invasion is present (I guess the twig that the surgeon cut was present in the sample and is being labelled Perineural invasion factor). SC is a low grade carcinoma and the margins are clear but they want me to go through the entire 6 weeks radiation treatment which they told me earlier was reserved for high grade malignancies. They say because of the tumor size and Perineural invasion 6 weeks is recommended. But I feel that radiation is expensive and might not be necessary. I need a 2nd opinion.