Is Itching a Sign of Cancer?

Itching is a complaint that most often has simple causes. It may result from an allergy or a drug side effect, but may sometimes be a sign of another underlying disease. So, when we experience chronic itching, should we consider the possibility of cancer? Before panicking, it is generally necessary to focus on more common causes of itching. Initially, newly used medicines, foods, detergents, and similar possible allergy triggers should be stopped and observed. If itching continues, a dermatologist should be consulted to investigate whether it has an allergic cause through a skin examination and some blood tests.

Conditions That May Cause Itching

Itching may have many different causes. Some of these are:

• Dry skin: Dryness of the skin, especially in winter or because of frequent bathing, is a common cause of itching.
• Jaundice: Jaundice due to liver or bile-duct problems (yellowing of the skin and whites of the eyes) may lead to itching.
• Allergy: Allergic reactions to substances such as foods, dust, pollen, animal hair, or detergents may cause skin itching.
• Infections: Fungal infections, parasites such as scabies, or other skin infections may cause intense itching.
• Cancer: Although rare, some cancer types may cause systemic itching (affecting the whole body).
• Cancer treatments: Cancer treatments such as chemotherapy and certain medicines used may cause itching (details are discussed below).

As can be seen, itching often has many causes other than cancer. So, is every itch a sign of cancer? Of course not; however, below we will examine certain situations to understand the relationship between cancer and itching in particular.

Can Itching Be a Sign of Cancer?

In general, itching originating in the skin is localized (regional) and does not spread throughout the body. Systemic itching, the widespread itching felt all over the body, is less common and may sometimes indicate a serious underlying condition. Although most cases of itching are unrelated to cancer, it is known that some cancer types can cause widespread itching in the body. In cases of cancer-related itching, fatigue, night sweats, jaundice, weight loss, and other symptoms often accompany the itching. In other words, rather than itching alone, there may be a combination of symptoms.

What Is Cancer-Related Itching Like?

There may be several basic mechanisms underlying itching in cancer patients:

• The tumor secreting certain substances: Some chemicals secreted by tumor cells may cause itching by producing effects in the body called paraneoplastic syndromes.
• Immune response: The body's immune response to a developing tumor may affect nerve endings in the skin, causing a sensation of itching.
• Bile-duct obstruction: Some cancers, especially those around the liver or pancreas, block the bile ducts and prevent bile flow. Jaundice developing as a result of this obstruction may cause intense itching.

Because of these mechanisms, patients with certain cancer types may experience generalized unexplained itching even before diagnosis. The cancer types most commonly associated with itching include lymphoma, leukemia, polycythemia vera (PV), certain gastrointestinal stromal tumors (GİST), as well as pancreatic and bile-duct tumors.

Below, the relationship between cancer and itching is examined through a few examples:

Itching in Leukemia (Blood Cancer) and Lymphoma

Hematological cancers such as leukemia (blood cancer) and lymphoma may rarely present with itching. Research suggests that, in these cancers originating from the blood and bone marrow, after immune-system cells come into contact with leukemia/lymphoma cells, high levels of cytokines are released, and these inflammatory molecules are thought to irritate nerve endings in the skin and cause itching.

Indeed, a survey called "Living Well with Leukaemia" (Living Well with Leukaemia) found that approximately 9% of leukemia patients had experienced, before diagnosis, itching as a symptom. A similar situation has been observed in Hodgkin lymphoma; according to oncologist Jennifer Crombie of the Dana-Farber Cancer Institute, among patients diagnosed with Hodgkin lymphoma, approximately 20% experienced itching as one of the symptoms that appeared before diagnosis of the disease.

Signs Suggesting That Itching Is Caused by Leukemia or Lymphoma:

In leukemia or lymphoma, for example, blood cancer-related itching does not usually occur alone.

The following symptoms occurring with itching may indicate an underlying blood disorder:

• Night sweats (episodes of excessive sweating at night)
• Unexplained weight loss (losing weight without dieting)
• Easy bruising (bruising after the slightest impact)
• Fever (unexplained, persistent fever)
• Joint and bone pain

If these symptoms accompany widespread itching, a doctor should be consulted without delay. They may suggest that the itching is due to leukemia, lymphoma, or a similar disease.

Polycythemia Vera (PV) and Itching

Polycythemia vera (PV) is a type of blood cancer characterized by uncontrolled excessive production of red blood cells in the bone marrow. Among PV patients, itching is quite common, and attacks may occur especially after a warm bath or hot shower (as the skin warms). This is also known in medicine as "aquagenic itching" and is a common finding in PV.

In addition to PV-related itching, there are other symptoms of this disease that should be considered.

Some important symptoms that may occur along with itching in polycythemia vera patients include:

• Shortness of breath even at rest (especially a feeling of breathlessness without exertion)
• Persistent fatigue and weakness
• Headache
• Dizziness and fluctuations in vision

If a person has intense itching together with the PV symptoms above, an underlying condition such as polycythemia vera or a similar hematological disease should be investigated.

Gastrointestinal Stromal Tumors (GİST) and Itching

Gastrointestinal stromal tumors (GİST) are rare tumors of the digestive system. In GİST cases, skin itching usually occurs as an indirect effect of the tumor. These tumors may press on the liver or bile ducts, causing bile-duct obstruction. When bile flow is obstructed, bile pigments accumulating in the blood cause yellowing of the skin (jaundice) and intense itching. In other words, the main cause of itching in GİST is a hepatobiliary system problem caused by the tumor.

With bile-duct obstruction, jaundice and itching may occur not only in GİST but also in other cancer types.

This is particularly common in the following cancers:

• Gastric cancer
• Colon (large bowel) cancer
• Pancreatic cancer
• Liver cancer
• Gallbladder and bile-duct cancers
• Gastrointestinal stromal tumors (GİST)

Therefore, itching accompanied by jaundice should prompt investigation for a tumor in these organs that could obstruct the bile ducts.

Can Cancer Treatment Cause Itching?

Like cancer itself, cancer treatments may also cause itching. Dry skin and rashes may occur especially during systemic treatments such as chemotherapy and immunotherapy, as well as radiotherapy (radiation treatment). In addition, targeted drugs (treatments directed at specific blocked molecules) and hormone therapies also have side effects that may cause itching. Certain supportive medicines used during treatment (for example, strong painkillers, morphine derivatives, anti-nausea medicines, or certain hormone medicines) may also produce itching as a side effect.

Generally, hormone therapy or targeted drug treatments are frequently associated with skin itching and rash. In this situation, patients may often worry, "Could I Be Allergic to the Treatment?" In fact, this itching is a known side effect of treatment rather than a true allergic reaction. Some researchers even suggest that itching in certain types of treatment may be a sign that the treatment is effective. Of course, if itching affects the patient's quality of life, anti-itch medicines or creams may be used in consultation with a doctor to relieve it.

Conclusion

Not Every Itch Means Cancer. Itchy skin on its own is typically not a sign of cancer. It most often has simple causes and can be relieved with appropriate measures. However, long-lasting, chronic, unexplained itching requires caution. If there is no obvious cause such as dry skin, itching is felt throughout the body, and other possible causes such as allergy, infection, eczema have been ruled out (that is, not found), persistent itching of unknown cause should always prompt a doctor's visit. In particular, accompanying signs such as night sweats, weight loss, fever should not be neglected, because these may signal a serious underlying disease. Remember, early diagnosis is vital in cancer treatment, as in every disease.