What factors do you typically consider when deciding whether to include retropharyngeal lymph nodes within your treatment volumes for squamous cell carcinoma of the oral cavity or oropharynx?  

I see no reason to treat the retropharyngeal nodal region prophylactically for oral cavity cancer as that is not pattern of spread for oral cavity. For oropharyngeal cancer we include the lateral retropharyngeal nodal region for all patients and include the medial retropharyngeals only if...

I agree with @Sushil Beriwal's response. However, I do not electively treat retropharyngeal LNs for primary tumors confined to the base of tongue.