Detection and Diagnosis of Malignancy (Part 3 of 3)

Question 1

what is a paraneoplastic syndrome?

Answer 1

when a tumor secretes substances such as PTH-rP or ACTH; or when the tumor evokes the elaboration of other factors like autoantibodies or cytokines

Question 2

what could cause hypercalcemia and a hypophosphatemic state if it isn’t PTH driven?

Answer 2

parathyroid hormone-related protein (PTH-rP)

Question 3

what is parathyroid hormone-related protein responsible for?

Answer 3

humoral hypercalcemia of malignancy

Question 4

what cancers tend to secrete PTH-rP?

Answer 4

squamous carcinomas (any site) lung, cancers of the breast, GI tract, and GU tract

Question 5

what does excess PTH-rP result in?

Answer 5

bone reabsorption and distal tubular calcium reabsorption; it does not affect vitamin D pathway and intestinal absorption of Ca

Question 6

how does hypercalcemia present?

Answer 6

significant drowsiness, AMS, tetany, arrythmias

Question 7

what would a low plasma sodium concentration, low serum osmolality, and an increased urine osmolality indicate?

Answer 7

the patient is not concentrating their urine appropriately

Question 8

why would a patient be inappropriately reclaiming free water?

Answer 8

they have syndrome of inappropriate ADH secretion (SIADH)

Question 9

what is syndrome of inappropriate ADH secretion?

Answer 9

secretion of ADH by tumor signals renal receptors to retain free water (rather than excreting it in the urine); this water dilutes the serum and causes mental status changes

Question 10

SIADH is the most common paraneoplastic syndrome in what cancer?

Answer 10

small cell neuroendocrine carcinoma

Question 11

small cell carcinoma has a significant risk of what?

Answer 11

many endocrine and neurologic paraneoplastic syndromes

Question 12

besides small cell neuroendocrine carcinoma, what other tumors are associated with SIADH?

Answer 12

squamous cell lung cancer, GI carcinomas, and GU carcinomas, and ovarian carcinomas

Question 13

if a patient present with new onset hypertension, hypokalemia, metabolic alkalosis, and muscle wasting, what might you suspect?

Answer 13

Ectopic ACTH secretion

Question 14

what is the number one cancer out there that is associated with a paraneoplastic syndrome?

Answer 14

small cell neuroendocrine carcinoma

Question 15

what is the second most common paraneoplastic syndrome associated with small cell neuroendocrine carcinoma?

Answer 15

Cushing disease from ectopic ACTH

Question 16

what are some examples of other tumors that are associated with ectopic ACTH secretion?

Answer 16

lung, bronchial carcinoid tumors, pancreatic islet tumors, medullary thyroid carcinoma, and pheochromocytoma

Question 17

what is lambert-eaton myasthenic syndrome?

Answer 17

another paraneoplastic syndrome; mediated typically by antibodies to voltage-gated calcium channels at the neuromuscular junction

Question 18

how do you screen for lambert-eaton myasthenic syndrome?

Answer 18

anti-VGCC antibodies

Question 19

what is lambert-eaton syndrome associated with?

Answer 19

malignancy, especially small cell