In reality, my decision making process for recommending IT therapy for cancer patients is fairly nuanced. It's definitely on a case by case basis. Most of my patients are very sick and complicated, to the point that I can't really apply a simple algorithm. There are just too many factors at play.
Nonetheless, broadly speaking, I opt for implantation of an intrathecal pump in cancer patients with neoplasm related pain, when the patient meets one of the following criteria:
1. Development of intolerable side effects from one or more pain medications that preclude effective usage of the medication(s), thereby resulting in poorly controlled pain, AND the patient either declines medication substitution or has already failed prior attempts at medication rotation to address the side effect issue.
2. The presence of persistently intractable pain despite maximal medical therapy AND this pain is either not amenable to other treatment modalities (other interventional pain procedures, palliative radiation, accupuncture, etc.) or the patient has already failed other treatment modalities. The big question here is what exactly constitutes "maximal medical therapy"? One of my partners is perfectly willing to titrate a cancer patient up to astronomically high dosages of systemic opioids (fentanyl patches in excess of 300 mcg, 90+ milligrams of oral dilaudid per day) before he reaches his ceiling for medical management of cancer pain. In stark contrast, I'm much more conservative when it comes to ceilings on systemic opioids for cancer pain. I don't have any fixed ceiling like 200 OMEs that I absolutely will not go above for any reason. Every patient is unique and there are some cancer pain patients who do quite well at OME dosages above 200. However, the term "medically refractory pain" definitely crosses my mind once a patient with terminal cancer reaches the 100-120 OME mark with a full complement of adjunctive medications on board, prompting me to explore other treatment options, including intrathecal therapy. I guess I'm on the conservative end of the spectrum when it comes to usage of systemic opioids in the treatment of cancer pain. They definitely play an important role, but I'm a bigger advocate for multidisciplinary, multi-modal therapy. Downstream effects from sustained, high dose systemic opioid therapy are too significant to ignore--things like the threat of opioid induced hyperalgesia, the development of extreme opioid tolerance (which makes postoperative pain control or management of acute on chronic exacerbations of pain an absolute nightmare to manage), the worsening of immunosuppression in patients with compromised immune systems already...the list goes on and on.
With respect to methadone, yes I definitely prescribe it. Some patients do EXTREMELY well on it, even when they have failed to respond favorably to more traditional opioid workhorses in cancer pain like fentanyl patches, morphine, oxycodone, etc. Should it be tried prior to implantation of an intrathecal pump? ABSOLUTELY! In fact, I consider methadone to be one of my first line drugs as a long acting systemic opioid for the treatment of cancer pain. I routinely prescribe the drug fairly early in the treatment process for my cancer pain patients. It's an excellent drug.
