Hi, Thanks for writing in. The palate is the most common site of minor salivary gland tumors. A minor salivary gland cancer requires treatment as per protocol. The radiation therapy was given to shrink the tumor mass and reduce it in size. Since these cancers might be slow growing as compared to other aggressive cancers, it is treated such that the chances of recurrence is less. The details and staging of minor salivary gland cancer in your mother is not mentioned and therefore it is possible that the treating doctor wants to reduce the tumor with radiotherapy. Since she is having pain in her inner mouth, it will help to get the oral cavity examined in detail to look for any post radiotherapy residual changes which are causing the symptoms. Some patients might develop mild dental infections after radiation therapy and this is treated with antibiotics should there be infection and pain relievers. Please do not worry.