A symptom, a warning and a mimic: paraneoplastic syndrome

Paraneoplastic syndromes are a group of diseases arising very rarely when cancer triggers the immune system through alternative pathways. A syndrome is a collection of seemingly unrelated findings that together manifest as a single condition.

A paraneoplastic syndrome is not directly related to the tumor or its spread to other tissues (metastasis); it results from tumor secretion of biologically active substances such as hormones or cytokines. These trigger symptoms involving many systems: endocrine, nervous, musculoskeletal, cardiovascular, skin, blood cells, gastrointestinal or kidneys.

One triggering mechanism is the immune response developed when tumor tissue appears. Normally immunity is programmed to defend against harmful external microorganisms. In autoimmune reactions, however, it attacks the body’s healthy tissues and damages them.

Although possible in many cancers, paraneoplastic syndromes occur most commonly in lung, breast and ovarian cancers and lymphomas.

When a patient presents with a paraneoplastic syndrome, the probability of underlying cancer ranges from %2-20.

Because clinical findings vary, syndromes are divided into subcategories:

1. Kidney syndromes: They cause imbalances in ions such as potassium, sodium and phosphate, needed for normal body function, and acid–base changes.
2. Gastrointestinal syndromes: They generally cause confusion, extreme fatigue and weakness through diarrhea-related mineral loss.
3. Hematological syndromes: They cause numerical blood-cell changes, including increases and decreases.
4. Endocrine syndromes: Tumor-secreted hormones alter levels of vital ions such as potassium and sodium. Because hormones suppressing immunity are secreted, this subgroup is most associated with mortality.
5. Skin syndromes: They cause discoloration, itching, thinning or thickening, redness, baldness and excessive hair growth.
6. Neuromuscular syndromes: They often cause memory loss, muscle weakness, excessive irritability and sensory loss in arms and legs.
7. Rheumatological syndromes: They present with skin hardening, substance deposits in tissues and joint damage.
8. Nonspecific syndromes: These include fever, poor appetite and altered taste not covered by other syndromes.

Paraneoplastic syndromes, with their numerous symptoms, can occur at all ages and have no association with race or sex. No method currently predicts which cancer patients will develop them.

Treatment varies by site and type. Two general approaches exist. First, target the tumor directly using chemotherapy, surgery and radiation separately or together. Studies show elimination of the tumor also eliminates paraneoplastic effects. Second, control the body’s antitumor immune response through removal of its defensive components, intravenous addition of new defensive components, immune-suppressing steroids or other drugs, and plasma exchange (plasmapheresis).

These syndromes may recur after treatment; drug dose adjustment varies according to the underlying cause.

In conclusion, Remembering the close cancer association helps early diagnosis. Paraneoplastic syndromes can also cause serious problems, so effective treatment improves quality of life, enhances cancer treatment effectiveness and prolongs survival.