1. It's expensive to start up an Oncology practice unless you turf all your chemo to an inpatient infusion unit (my medium sized office has 5 front desk staff, 6-8 RNs depending on the day, 3-4 MAs, a pharmacist and 2 pharm techs, a lab tech and 2 people whose FT job is doing prior auths...and that doesn't count the 4 docs and 1 NP). Or have a turnkey thing with something like US Oncology, in which case, they're going to be making the money off the chemo, not you. Buy and bill is too expensive for many smaller groups, especially with the pricing that academics and non-profits get.
2. Hospitals are buying up PP groups like they're going out of style. For senior partners, this can be a good thing since theyll get a pretty nice payout in lieu of decreased annual compensation. Sucks for the junior folks though.
As a very practical example, in my medium-sized metro area, 10 years ago there were 7 PP groups, the University Hospital and a Kaiser hospital. Today, all but 2 of the PP groups have been bought by various hospitals. One of those 2 remaining PP groups is looking to sell but can't find a buyer, the other is a US Oncology group and is hemorrhaging docs (6 down in the last 3 years, none hired)