What pain syndromes occur in patients with cancer?
PHN, defined as persistence of pain for weeks or months after complete resolution of the herpes zoster (shingles) rash, can follow an episode of shingles in a cancer patient. While advanced age (related to waning cell-mediated immunity) is the most common factor associated with development of PHN, those with immunosuppression or cancer are most likely to develop PHN. The Shingles Prevention Study showed that immunization against herpes zoster decreased overall incidence of shingles and reduced the incidence of PHN by 65% in individuals over age 60. The Advisory Council on Immunization Practice recommends that all individuals receive zoster immunization at age 60. Patients newly diagnosed with cancer should receive zoster immunization as soon as possible prior to initiation of chemotherapy. A recent study of the new herpes zoster subunit vaccine (HZ/su) showed that vaccine efficacy against herpes zoster was 91.3%, and vaccine efficacy against PHN was 88.8%.
In addition to the risk for shingles/PHN, many common chemotherapeutic agents cause mucositis and some therapies (e.g., everolimus, sorafenib, regorafenib) cause painful stomatitis. Frequency and severity are both drug- and dose-dependent. Three commonly used cytotoxic agents associated with oral mucositis are doxorubicin, fluorouracil, and methotrexate. Mucositis develops in nearly all patients receiving radiation treatment (RT) to the head and neck region. RT-induced mucositis is similar to that induced by chemotherapy, usually developing 2 to 3 weeks after starting treatment. Incidence and severity of RT-induced mucositis depend on the field, total dose and duration of RT, and the use of concomitant chemotherapy. Anticipatory treatment may include oral lubricants and mouthwash containing antihistamine or local anesthetic to reduce pain and discomfort, antibiotic (bactericidal), antifungal, corticosteroid (antiinflammatory), and an antacid to ensure the other ingredients adequately coat the buccal mucosa. Most pharmacies compound such a substance, known as Magic Mouthwash.