Lab Assessment of Tumor Markers Flashcards
What are the clinical utilities for tumor markers?
screening early detection differential diagnosis in symptomatic patients clinical staging estimating tumor volume prognosis predicting of treatment response monitoring of therapy detecting of cancer recurrence
How would you interpret the following results: Total PSA 5.2, % free PSA 28%
PSA is elevated
then use the %free PSA to determine the probability of cancer. The higher the percent PSA, the LESS likely it’s cancerous. >25% free has only an 8% probability of cancer
(note, only check this if the PSA is between 4 and 10. if it’s over 10, the risk of cancer is already over 50%)
What are some pre-analytical factors that affect tthe PSA?
biological variation prostate manipulation (DRE, needle biopsy, ejactulation) exercise (esp biking) prostatitis drugs (finasteride)
What is the intended use of the PCA3 assay?
to aid in clinical decisions for when to re-biopsy patients who were previously biopsy-negative for prostate cancer
BUT - recommendations are currently against use even though it’s FDA approved
Describe the high dose hook (prozone) effect?
If you have an excess amount of antigen binding to either the capture or labeled antibody of a lab test, then you don’t get the desired “sandwich” complex and the result will be lower than anticipated
How can you identify if a high dose hook effect has occurred?
you assay the same specimen at two dilutions. If the result is higher at the lower dilution, then you know the effect is occurring
What is the intended use for CA125?
It’s indicated as a ONE-TIME test for use as an aid in the detection of residual ovarian Ca after first-line therapy
helps to decide if you need a second-look procedure
A CA125 assay value greater than what is indicative of residual disease?
35 U/mL
provided that alternative causes of an elevated CA125 can be excluded
What are some non-cancer conditions that will elevate the CA125?
menstruation first trimester of pregnancy CHF TB Cirrhosis Fibroids Benign ovarian tumors Endometriosis
What are some non-gynecological cancers that will elevate the CA125?
liver Ca
Lung ca
Breast Ca
Pancreatic Ca
What marker can be used to monitor recurrence or progressive disease in patients with epithelial ovarian cancer?
human epididymis protein 4 (HE4)
WHy is HE4 particularly useful?
It is more specific to cancer than CA125, so you can use it when the patient has a re-elevation of CA125 and you want to assess for cancer recurrence
What algorithm utilizes both the HE4 and CA125?
the Risk of Ovarian Malignancy Algorithm (ROMA)
OVA1 is another lab algorithm that can be used to further assess the likelihood of malignancy. What labs go into this?
CA125 + Prealbumin + Apolipoprotein A-1 + Beta2- microglobulin + Transferrin
