I'm not sure exactly what your objection to the Oregon law is, or how you would like to see it overturned without granting the federal government dangerously-broad commerce clause authority.
The law works like this - someone who is diagnosed as being in the late stages of terminal illness (by 2 doctors) can apply to get a prescription for a lethal dose of drugs.
The doctor doesn't "kill them," the doctor just writes the prescription. The patient gets the prescription filled, and then has the drugs on-hand - some people never use the drugs. They pass away with no assistance, or they decide that their pain is bearable. So, even though a doctor gave them the option of taking the drugs, no "assisted suicide" takes place.
This is because some patients want the drugs as a last-resort; a safety mechanism that can be used if things become unbearable for them. It is very comforting for some terminal patients to have this option, especially given the persecution of pain-management specialists under federal drug laws.
This is not a new thing - in fact, family doctors have been giving people "a little extra medicine" in their last days since medicine has existed. It was recognized throughout modern times that this was one of the roles of a physician, as a person who eased the passage from life to death for people in the final throes of terminal conditions.
So, in the not-so-distant past, an "assisted suicide" statute would have been redundant, since that was something that a physician could already provide. However, in modern times, drug regimens and end-of-life treatment has gotten far more controlled and sophisticated. In a big way, the "assisted suicide" legislation was a way to restore to patients the role that the family doctor had to relinquish due to changing times and technology.
Now, note that there is nowhere in the federal drug code stating that "doctors cannot prescribe end-of-life patients with lethal doses of medication." That phrase, or something like it, has been inferred; which means that the federal government wants to trump a state law on the basis of a shadow of a contradiction. It means that the feds want to rule people's lives, again, via the commerce clause.
There is no similarity here to abortion - abortion is about deprivation of a right to life. It is a rights-taking measure. The assisted-suicide statute is a rights-granting measure. No one exerts their power or control over anyone else under that law; it is a patient-directed decision. Federal intervention against it would actually be more akin to abortion, in the way that it would be another rights-taking measure - and at the expense of state's rights.
And that approach should trouble small-government conservatives.
And doctors in particular should be barred by their oath, at the very least, and then by law, from killing their patients in this manner.