What is paraneoplastic syndrome

Paraneoplastic syndrome is a group of symptoms that may develop when substances released by some cancer cells disrupt the normal function of surrounding cells and tissue. Paraneoplastic syndromes are thought to happen when cancer-fighting antibodies or white blood cells (known as T cells) mistakenly attack normal cells in the neurological, dermatological, gastrointestinal, endocrine, hematologic, and cardiovascular systems ¹. In other words, cancer cells do not directly manifest symptoms with metastasis; rather the cancer cells generate autoantibodies, cytokines, hormones, or peptides that affect the multiple organ systems such as neurological, dermatological, gastrointestinal, endocrine, hematologic, and cardiovascular system, but the exact mechanism remains unclear ².

Paraneoplastic syndrome typically affects middle-aged to older people and are most common in individuals with lung cancer, breast cancer, hematological malignancies, medullary thyroid cancer, gynecological malignancies, and prostate cancer ³. Precise incidence and prevalence of the paraneoplastic syndrome are unknown because of the rarity of disease; however, it can occur with any malignancy. A review of the literature suggests that paraneoplastic syndrome occurs in up to 8% of cancer patients ⁴. Neurological manifestation in the form of neuropathies is common. Males and females are affected equally.

Neurologic symptoms generally develop over a period of days to weeks and usually occur prior to the tumor being discovered. Paraneoplastic syndrome symptoms may include difficulty in walking or swallowing, loss of muscle tone, loss of fine motor coordination, slurred speech, memory loss, vision problems, sleep disturbances, dementia, seizures, sensory loss in the limbs, and vertigo or dizziness. Paraneoplastic syndromes include Lambert-Eaton myasthenic syndrome, stiff-person syndrome, encephalomyelitis, myasthenia gravis, cerebellar degeneration, limbic or brainstem encephalitis, neuromyotonia, opsoclonus, and sensory neuropathy.

Paraneoplastic syndrome pathophysiology

Tumor cells are immunogenic and lead to the activation of both cell-mediated and humoral immune systems. It has been observed that cytotoxic T cells recognize antigens on tumor cells and attack those cells or generate antibodies against tumor cells ⁵. However, the body’s immune system can also attack normal tissue with a similar antigen presentation and lead to symptoms. Most cases exhibit paraneoplastic syndrome with immunologic mechanisms; however, there are non-immunologic mechanisms of paraneoplastic syndrome. Paraneoplastic syndrome has heterogenous manifestations affecting multiple organ systems in the body, and clinical manifestation does not necessarily associate with the clinical or pathological stage of the underlying malignancy nor is it a prognostic indicator ⁶.

Immunologic mechanism

Cell-mediated immunity, T cells attack tumor cells antigens as well as similar antigens in normal cells.

Paraneoplastic antibodies, also known as onconeural antibodies, direct against target antigen (onconeural antigen) such as type-1 antineuronal nuclear antibodies (ANNA-1), type-2 antineuronal nuclear antibodies (ANNA-2), collapsing response mediator protein-5 (CRMP-5), Purkinje cell cytoplasmic antibody type-1 (PCA-1), anti-amphiphysin, anti-recoverin, anti-bipolar cells of the retina, N-methyl D-aspartate (NMDA) receptor antibodies, acetylcholine receptor antibodies, and gamma-aminobutyric acid A (GABA-A) receptor antibodies.

Non-immunologic mechanism

Tumor cells produce hormones or cytokines leading to metabolic abnormalities such as hyponatremia due to antidiuretic hormone or hypercalcemia due to the parathyroid-hormone related peptide. Hematological malignancies producing immunoglobulins affect the peripheral nervous system manifested as peripheral neuropathy.

Paraneoplastic syndrome symptoms

Paraneoplastic syndrome involves multi-organ system in the body with diverse and complex clinical signs and symptoms in the setting of underlying malignancy.

Clinical presentations are categorized based on the organ system as follows.

Nervous system

Signs and symptoms are based on the part of the nervous system that is affected by a paraneoplastic syndrome, for example, central nervous system, neuromuscular junction, or peripheral nervous system. A patient may present with seizure, cognitive dysfunction, personality change, psychosis, insomnia, ataxia, dysarthria, dysphagia, cranial nerve deficits, and sensorimotor abnormalities.

Central nervous system

Paraneoplastic encephalitis/encephalomyelitis

Diverse and complex symptoms arising from cerebellar encephalitis, brainstem encephalitis, limbic encephalitis, and myelitis. Characterized by cognitive dysfunction, depression, personality changes, hallucinations, seizures, somnolence, autonomic dysfunction, and less commonly endocrine dysfunction if the hypothalamus is involved ⁷.

Subacute cerebellar degeneration

It is commonly associated with breast cancer, small cell lung cancer, Hodgkin lymphoma, and ovarian cancer. Clinically manifested as ataxia, dysarthria, dysphagia, diplopia, dizziness, nausea, and vomiting.

Opsoclonus-myoclonus syndrome

Clinically characterized by uncontrolled rapid eye movement, body jerks, ataxia, hypotonia, irritability and commonly affects children less than 4 years. Opsoclonus is the common manifestation in children whereas ataxia is more prominent in adults.

Neuromuscular Junction

Myasthenia Gravis

Most commonly seen in patients with thymoma and is clinically manifested as a weakness of voluntary muscles and diaphragmatic weakness. Anti-AchR (acetylcholine receptor) antibody is positive in those patients, and electromyography (EMG) shows a decremental response to repetitive nerve stimulation ⁸.

Lambert-Eaton myasthenic syndrome

It is caused due to impairment of voltage-gated calcium channels (VGCC) due to autoantibodies on the presynaptic membrane at neuromuscular junction which leads to decreased acetylcholine release ⁸. Lambert-Eaton myasthenic syndrome is strongly associated with small cell lung cancer, about 3% of patients develop Lambert-Eaton myasthenic syndrome, and it can occur at any stage of the disease. Clinically Lambert-Eaton myasthenic syndrome is characterized by weakness of the proximal muscles predominantly affecting thigh and pelvic muscles; patient generally have difficulty in strenuous activity; moreover, patients also have difficulties in basic activities such as climbing stairs, walking, and getting up from a chair. Symptoms are gradual in onset with slow progression. Patients also demonstrate autonomic symptoms such as dry mouth, decreased sweating, and constipation. Clinical examination is positive for diminished tendon reflexes. The blood anti-voltage-gated calcium channels antibodies are positive in approximately 85% of patients with Lambert-Eaton myasthenic syndrome.

Peripheral Nervous System

Autonomic neuropathy

Frequently associated with small cell lung cancer and thymoma. Autonomic neuropathy affects parasympathetic, sympathetic, and enteric nervous systems. Characterized by dry mouth, eyes, altered pupillary reflexes, bladder and bowel dysfunction, orthostatic hypotension. A patient may also manifest as chronic gastrointestinal (GI) pseudo-obstruction leading to constipation, nausea, vomiting, dysphagia, and abdominal distension.

Subacute sensory neuropathy

Characterized by paresthesia, pain, decreased sensation and deep tendon reflexes. It affects both upper and the lower extremities; distribution can be either multifocal, asymmetric or symmetric.

Endocrine

Cushing syndrome

Manifested as muscle weakness, weight gain, peripheral edema, centripetal fat distribution, and high blood pressure ⁹. Blood workup significant for hypokalemia elevated cortisol level and elevated ectopic adrenocorticotropic hormone (ACTH) due to tumor cells.

Syndrome of inappropriate antidiuretic hormone secretion (SIADH)

Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is more frequently seen in small cell lung cancer patients due to ectopic anti-diuretic hormone (ADH) by tumor cells ¹⁰. Clinical manifestations vary from mild symptoms such as nausea, anorexia, fatigue, and lethargy to severe symptoms like confusion, seizures, respiratory depression, and coma. Laboratory findings are positive for hyponatremia, hyperosmolality and increased urine osmolality.

Hypercalcemia

It is frequently associated with lung cancer, multiple myeloma, and renal cell carcinoma. Hypercalcemia is mediated by different mechanisms such as the ectopic production of the parathyroid hormone-related peptide by tumor cells, local osteolytic hypercalcemia and increased excess extrarenal vitamin D. Patients manifest as generalized weakness, lethargy, nausea, vomiting, altered mental status, bradycardia, acute renal failure, hypertonia, and hypertension.

Rheumatological

Paraneoplastic polyarthritis

Commonly involves large joints and is characterized by migratory, non-erosive, asymmetric polyarthritis.

Polymyalgia rheumatica

Manifested as pain and stiffness in the shoulder girdle, neck, and hip girdle ¹¹. It is most commonly associated with myelodysplastic syndrome.

Multicentric reticulohistiocytosis

Clinically characterized by papules, nodules, and destructive polyarthritis.

Hypertrophic osteoarthropathy

Clinically manifested as digital clubbing, joint swelling, and pain.

Hematological

Hematologic manifestations of the paraneoplastic syndrome are generally asymptomatic but can be manifested as pallor, fatigue, dyspnea, and venous thromboembolism. Hematologic syndromes are characterized by thrombocytosis, granulocytosis, eosinophilia, pure red cell aplasia, disseminated intravascular coagulation, and leukemoid reactions.

Dermatological

Acanthosis nigricans

Manifested as thickened hyperpigmented skin, usually in the axilla and neck region. Gastric adenocarcinoma is most commonly associated with acanthosis nigricans ¹².

Paraneoplastic pemphigus

Characterized by blistering and erosion of trunk, palms, and soles; also involves mucous membrane causing pain due to mucosal erosion. Commonly seen in patients with B-cell lymphoproliferative disorder ¹³.

Sweet syndrome

This is also known as acute febrile neutrophilic dermatosis. It manifests as acute onset of painful, erythematous plaques, papules, and nodules accompanied by fever and neutrophilia.

Leukocytoclastic vasculitis

Typically manifests as palpable purpura on the lower extremities, but a patient may also experience cyanosis, pruritus, pain, and ulceration of the affected skin.

Dermatomyositis

Characterized by a heliotrope rash on the upper eyelids, Gottron papules on phalangeal joints, and an erythematous rash on the face, neck back, chest, and shoulders ¹². Also involves muscles as inflammatory myopathy and is manifested as proximal muscle weakness and muscle tenderness.

Renal

Electrolyte imbalance (hypokalemia, hypo or hypernatremia, hyperphosphatemia) causing nephropathy and acid-base disturbance due to ectopic hormones produced by tumor cells such as ACTH and ADH ¹⁴. Nephrotic syndrome can also be one of the manifestations of paraneoplastic syndrome.

Other symptoms

Fever, cachexia, anorexia and dysgeusia (distortion of the sense of taste).

Paraneoplastic syndrome diagnosis

Diagnosis of the suspected paraneoplastic syndromes is based on the exclusion of other etiologies as there are heterogeneous clinical manifestations.

An international panel of neurologists developed criteria for paraneoplastic syndrome affecting the nervous system into definite and possible categories ¹⁵.

Definite paraneoplastic syndrome

A classical neurological syndrome and malignancy which develops within 5 years of neurological disorder. Classical syndromes are encephalomyelitis, limbic encephalitis, subacute cerebellar degeneration, opsoclonus-myoclonus syndrome, Lambert Eaton myasthenic syndrome, subacute sensory neuropathy, chronic gastrointestinal pseudoobstruction, and dermatomyositis.

1. A nonclassical syndrome that improves significantly with the treatment of underlying malignancy and syndrome is not prone to spontaneous remission.
2. A nonclassical syndrome with the detection of paraneoplastic antibodies and malignancy that develops within 5 years of diagnosis of the neurological syndrome.
3. A classical or nonclassical neurological syndrome with well-recognized paraneoplastic antibodies. The well-recognized antibodies include anti-Hu, Yo, Ri, CV2/CRMP-5, Ma2, and amphiphysin.

Possible paraneoplastic syndrome

1. A classical syndrome without paraneoplastic antibodies and cancer but at high risk for an underlying malignancy.
2. A classical or nonclassical neurologic syndrome with partially characterized antibody but no cancer.
3. A nonclassical syndrome without paraneoplastic antibodies but with cancer within 2 years of a neurological syndrome.

A patient should be evaluated with a complete panel of laboratory, imaging, electrodiagnostic studies and biopsy of specific tissues if required.

• Complete blood count with differential
• Comprehensive metabolic panel
• Urinalysis
• Tumor markers
• Ectopic hormones level like parathyroid hormone-related peptide, ACTH, ADH
• Cerebrospinal fluid analysis (CSF)
• Protein electrophoresis o serum and CSF
• Assay of paraneoplastic antibodies in blood and CSF
• Skin biopsy
• Muscle biopsy

Paraneoplastic syndrome treatment

When present, the tumor and cancer are treated first with chemotherapy, radiation, or surgery, followed by efforts to decrease the autoimmune response — either through steroids such as cortisone or prednisone, high-dose intravenous immunoglobulin, or irradiation. Plasmapheresis, a process that cleanses antibodies from the blood, may ease symptoms in people with paraneoplastic disorders that affect the peripheral nervous system. Speech and physical therapy may help individuals regain some functions.

Paraneoplastic syndrome life expectancy

There are no cures for paraneoplastic syndromes. There are no available treatments to stop progressive neurological damage. Generally, the stage of cancer at diagnosis determines the outcome.

References

1. Thapa B, Ramphul K. Paraneoplastic Syndromes. [Updated 2019 May 5]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK507890
2. Pelosof LC, Gerber DE. Paraneoplastic syndromes: an approach to diagnosis and treatment. Mayo Clin. Proc. 2010 Sep;85(9):838-54
3. Zuliani L, Graus F, Giometto B, Bien C, Vincent A. Central nervous system neuronal surface antibody associated syndromes: review and guidelines for recognition. J. Neurol. Neurosurg. Psychiatry. 2012 Jun;83(6):638-45
4. Baijens LW, Manni JJ. Paraneoplastic syndromes in patients with primary malignancies of the head and neck. Four cases and a review of the literature. Eur Arch Otorhinolaryngol. 2006 Jan;263(1):32-6
5. Zaborowski MP, Michalak S. Cell-mediated immune responses in paraneoplastic neurological syndromes. Clin. Dev. Immunol. 2013;2013:630602
6. Spinazzé S, Schrijvers D. Metabolic emergencies. Crit. Rev. Oncol. Hematol. 2006 Apr;58(1):79-89
7. Grisold W, Giometto B, Vitaliani R, Oberndorfer S. Current approaches to the treatment of paraneoplastic encephalitis. Ther Adv Neurol Disord. 2011 Jul;4(4):237-48
8. van Sonderen A, Wirtz PW, Verschuuren JJ, Titulaer MJ. Paraneoplastic syndromes of the neuromuscular junction: therapeutic options in myasthenia gravis, lambert-eaton myasthenic syndrome, and neuromyotonia. Curr Treat Options Neurol. 2013 Apr;15(2):224-39
9. Barbosa SL, Rodien P, Leboulleux S, Niccoli-Sire P, Kraimps JL, Caron P, Archambeaud-Mouveroux F, Conte-Devolx B, Rohmer V., Groupe d’Etude des Tumeurs Endocrines. Ectopic adrenocorticotropic hormone-syndrome in medullary carcinoma of the thyroid: a retrospective analysis and review of the literature. Thyroid. 2005 Jun;15(6):618-23
10. Peri A, Grohé C, Berardi R, Runkle I. SIADH: differential diagnosis and clinical management. Endocrine. 2017 Jan;55(1):311-319
11. Muller S, Hider S, Helliwell T, Partington R, Mallen C. The real evidence for polymyalgia rheumatica as a paraneoplastic syndrome. Reumatismo. 2018 Mar 27;70(1):23-34.
12. Dourmishev LA, Draganov PV. Paraneoplastic dermatological manifestation of gastrointestinal malignancies. World J. Gastroenterol. 2009 Sep 21;15(35):4372-9
13. Wick MR, Patterson JW. Cutaneous paraneoplastic syndromes. Semin Diagn Pathol. 2019 Jan 31
14. Dhanapriya J, Dineshkumar T, Sakthirajan R, Surendar D, Gopalakrishnan N, Balasubramaniyan T. Paraneoplastic glomerulopathies associated with hematologic malignancies. Saudi J Kidney Dis Transpl. 2018 Mar-Apr;29(2):452-455
15. Graus F, Delattre JY, Antoine JC, Dalmau J, Giometto B, Grisold W, Honnorat J, Smitt PS, Vedeler Ch, Verschuuren JJ, Vincent A, Voltz R. Recommended diagnostic criteria for paraneoplastic neurological syndromes. J. Neurol. Neurosurg. Psychiatry. 2004 Aug;75(8):1135-40