CancerConnect News: Epidermal Growth Factor Receptor (EGFR) inhibitor drugs are a type of precision cancer medicine commonly used to treat lung, colon, head and neck and other cancers that over express the EGFR. There are several EGFR inhibitor drugs and these cause similar side effects.
The EGFR pathway is a normal biologic pathway found in healthy cells. It is involved in regular cellular division and growth. However, certain mutations within the EGFR gene can lead to an overactive EGFR pathway, leading to the development and/or spread of cancer. These cancers are referred to as EGFR-positive, and there are several FDA-approved medications to block the activity of EGFR and slow cancer growth for EGFR-positive cancers. EGFR mutations are most common in individuals who never smoked, woman, people of Asian ethnicity, and those with a type of lung cancer known as adenocarcinoma.
Unique side effects of all EGFR inhibitors include:
Skin rash: The most commonly seen side effect from EGFR inhibitors is a papulopustular skin rash that erupts most often on the face but can also be seen on the chest, back, trunk, and limbs. It tends to be associated with dry skin and at times can be diffuse and very disruptive. The rash commonly manifests in the first 1 to 2 weeks of treatment.
Other skin and hair side effects may include alopecia (hair loss), paronychias (nail damage), conjunctivitis, skin fissures, and generalized pruritus.
With longer-term use of EGFR inhibitors, other dermatologic effects can occur.
Paronychias Inflammation and soreness around the nail bed is known as paronychias which can be difficult to treat.
Fingertip splitting from very dry skin is also a later side effect. Prescription-strength urea moisturizers and glues such as Superglue or Liquid Bandaid can be utilized for treatment. Be sure to not exposing fingers to extreme temperatures or friction; this may exacerbate the splitting or paronychias.
Alopecia or hair thinning can occur from EGFR inhibitor use. The alopecia is usually partial rather than complete, as occurs with chemotherapy; however, the hair can become brittle and fall out in clumps. This side effect can be worse if the papulopustular rash is present on the scalp. Therapeutic shampoos, such as OTC t-gel shampoos or prescription-strength shampoos such as fluocinolone acetonide (Capex), can help moisturize the scalp. The eyelashes and eyebrows can also grow long and brittle, sometimes curling inward toward the eye. To avoid corneal abrasions, the eyelashes should be kept trimmed.
Diarrhea is another common side effect and can occur at any time during treatment with EGFR inhibitors. Other less common GI side effects can be nausea and vomiting, anorexia, and stomatitis.
Recommended dietary guidelines for diarrhea
If OTC products are not effective, a prescription medication such as diphenoxylate/atropine (Lomotil) can offer stronger relief.
Reduction in EGFR inhibitor dose may be necessary if the diarrhea persists. A patient who is having persistent diarrhea should be monitored for electrolyte imbalances, such as low magnesium and potassium levels.
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