Chemotherapy is a powerful cancer treatment that can sometimes lead to unexpected responses. A chemotherapy hypersensitivity reaction, often called an allergic reaction, occurs when the body’s immune system overreacts to the drug. This differs from common chemotherapy side effects, which result from the drug’s intended action on rapidly dividing cells, both cancerous and healthy. These reactions are typically manageable, and medical teams are prepared to address them.
Prevalence of Chemotherapy Hypersensitivity
The commonality of hypersensitivity reactions to chemotherapy drugs varies significantly by specific agent. Platinum-based drugs, such as carboplatin, oxaliplatin, and cisplatin, along with taxanes like paclitaxel and docetaxel, are most frequently associated with these reactions. For instance, carboplatin hypersensitivity incidence ranges from 2.6% to 16% in some patient populations, and up to 44% in second- and third-line settings. This often increases with repeated exposure, with rates of 12-33% reported in women retreated with carboplatin, often peaking around the eighth cycle.
Paclitaxel can also induce hypersensitivity reactions, with reported incidences varying widely from 2% to 63%. With premedication, paclitaxel incidence can be reduced to between 1% and 3%, usually occurring within the first or second dose. Other chemotherapy drugs, including L-asparaginase, etoposide, and procarbazine, also cause hypersensitivity reactions, though generally less frequently than platinum agents and taxanes.
Recognizing Reaction Signs
Hypersensitivity reactions to chemotherapy can manifest with a wide range of symptoms, from mild to severe. Skin reactions are common, including hives, itching, rash, or redness and flushing of the face and neck. Respiratory symptoms may include wheezing, shortness of breath, or difficulty breathing, and throat swelling. Cardiovascular changes can involve a fast heartbeat, changes in blood pressure (either high or low), or chest discomfort. Gastrointestinal issues like nausea, vomiting, or abdominal pain can also occur.
These reactions can develop rapidly, often within minutes of drug administration, characteristic of an anaphylactic response. However, delayed reactions, appearing days or even weeks after an infusion, are also possible. Patients should promptly report any unusual or new symptoms to their healthcare team.
Understanding Causes and Risk Factors
Hypersensitivity reactions occur when the immune system mistakenly identifies a chemotherapy drug as harmful. This immune response activates mast cells and basophils, releasing chemical mediators like histamine. Some reactions are IgE-mediated, indicating a true allergic response, while others are non-IgE mediated, sometimes called pseudoallergic reactions.
Several factors can increase a patient’s likelihood of experiencing a reaction. Prior exposure to similar drugs is a significant risk factor, particularly for platinum compounds where reactions often appear after multiple cycles. A history of other drug allergies can also elevate the risk. Certain chemotherapy agents inherently have a higher propensity for causing reactions due to their chemical structure or excipients. While not fully understood, individual predispositions like gender (reactions are more common in women), age, or certain genetic factors may also play a role.
Managing and Preventing Reactions
When a hypersensitivity reaction occurs, the immediate step is to stop the chemotherapy infusion. Depending on symptoms, medical staff may administer medications such as antihistamines to block histamine effects, corticosteroids to reduce inflammation, and in severe cases, epinephrine to counter a systemic reaction. Oxygen may also be given for difficulty breathing. Medical staff are trained to assess the patient’s airway, breathing, and circulation and to provide supportive care.
To minimize reaction risk, especially with drugs known for higher hypersensitivity rates, premedication is a common preventive measure. This often involves administering corticosteroids, antihistamines (H1 and H2 blockers), and sometimes other agents before the infusion. For patients who have experienced a reaction and for whom chemotherapy is still the most effective treatment, desensitization protocols may be used. These protocols involve administering the drug in gradually increasing, very small doses over a controlled period, allowing the immune system to temporarily tolerate the medication. This procedure is typically performed in a monitored setting, allowing many patients to continue receiving essential treatment.