Paraneoplastic syndrome

Refers to signs and symptoms of organ damage remote from the site of a primary malignancy or its metastases.

Best described paraneoplastic syndromes are related to tumor secretion of functional peptides and hormones or immune cross-reactivity between tumor and normal host tissues.

May occur before the diagnosis of cancer, and is most commonly seen with neurologic paraneoplastic disorders.

Affects up to 8% of patients with cancer (Baijens LW).

Because endocrine paraneoplastic syndromes are a result of tumor production of hormones or peptides that cause metabolic abnormalities, successful treatment of the cancer can often improve the syndrome.

The development of paraneoplastic syndromes does not necessarily correlate with the stage of the malignancy or its prognosis (Raftopoulos H).

Paraneoplastic endocrine syndromes include: SIADH, hypercalcemia, Cushing’s disease, hypoglycemia.

Rare affecting approximately 0.01 percent of patients with malignancy.

Most commonly immune mediated.

Neurologic disorder usually appears before the cancer.

Neurologic symptoms appear in 60% of patients with paraneoplastic disorders before the diagnosis of cancer.

The absence of a known cancer in such cases reflects that the antitumor immune response may contribute to the small size of the tumor making diagnosis difficult.

Antibodies are necessary but not sufficient alone to cause neurologic dysfunction and cytotoxic T-cell responses are involved.

No antibodies are identified in about 40% of cases.

Some patients with small cell  cancer have direct voltage gated calcium channels antibodies, and antibodies that cross react with small cell carcinoma antigens and human neuronal RNA binding proteins resulting in multiple neurological deficits.

Paraneoplastic antibody panels are available.

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