I am a little late in responding to this, but I hope you see my post.
I am a fellow stage 4 breast cancer survivor. I applied for and was immediately approved for social security a few weeks after my dx. That was back in March 2012. I have been counting down the 2 year waiting period for Medicare.
Right now I am covered under my husband's insurance plan, which has a $10,000 out of pocket maximum. So every year we have to pay the first $10,000 before they will pay and then they only pay 80%. To help defray part of the $10,000 my oncologist office helped me reach out to several agencies such as the Patient Access Network, which provides grants to women in our situations. Speak to somone within the billing department of your oncologist office to see if this is something they can help you with.
Also, you may not qualify for Medicaid now but after a few months of treatment that may change. I am not sure if the Medicaid rules are the same from state to state, but here in New York if you reach a set dollar amount within a three month period, Medcaid will help out regardless of your financial situation. I am not sure as to specifics, but you may want to look into this further as the same rules may apply in your state.
Don't stop treatment because of money issues. There are multiple organizations out there that can help, its just a matter of reaching out to them. Your oncologist office or your local hospital should be able to help you locate the organizations in your area.
As a side note - my oncologist bill this year so far has totalled well over $50k. I received a bill last month for $8,000 (the amount my insurance did not cover). I reached out to the ladies in the billing department letting them know that there was no way I could come up with $8,000. They had me send in a few forms (including last years tax return) and they were able to adjust my bill down to $350. Much more reasonable! Reach out to your doctor's office, they really are there to help in more ways than just medically.