Know about Adenosquamous Carcinoma?

My 77-year-old Father was recently diagnosed with invasive adenosquamous carcinoma of the lung. My Mother just passed from adenocarcinoma of the lung last December, so needless to say it's a shock to the family that we're facing it yet again.

My understanding is that adenosquamous is a combination of both adeno and squamous cells in the same tumor, and that it's very rare. His tumor is 2.1 cm, and we are now scheduled for MRI of the brain, and a PET scan next week to determine staging.

The oncologist seems fairly confident that the tumor will be localized, and if that's the case, Dad will be treated using Cyberknife. We were surprised at the reaction the oncologist had to the pathology report...because of the two types of cells in one tumor...he almost acted like it was wrong, or that the pathologist was uncertain of the type.

Everything I have read on the internet indicates that this is a very rare and agressive type of lung cancer. Because of the rarity, there is not much information out there other than a few studies from years ago.

Does anyone have more info or personal experience with adenosquamous carcinoma?
Thank you, and God bless!