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CA 15.3

About the test
What is this test done for?
CA 15-3, i.e. Carcinoma Antigen 15-3, also known as MUC1, is a tumor marker test for Breast Cancer.
Why is it Done?

This is a specialized test for detecting metastatic breast cancer and it is done for

  • Ruling out spreading breast cancer
  • Monitoring the response to breast cancer treatment
  • Surveying patient for recurrence of disease after the treatment of metastatic breast cancer
When should it be performed?

This test is performed

  • When the patient has symptoms like
    • A lump in breast and palpable lymph nodes
    • Nipple discharge (especially blood stained)
    • Lump or thickening of breast or underarm
  • While the patient is receiving the chemotherapy or radiotherapy for metastatic breast cancer
  • As a routine screening test after the treatment of metastatic breast cancer is over
How is it done
A blood sample will be collected from a vein in your arm. No special preparations like fasting required. Avoid use of multivitamins or dietary supplements having Biotin or Vitamin B7 for about 12 hours before the test.

The test is negative if levels are < 30 U/mL

  • Absence of metastatic disease (if done primarily to confirm metastatic breast cancer)
  • If the tumor has responded well to the chemo-radiotherapy
  • Absence of recurrence of disease

Positive, if levels are > 30 U/mL

  • Presence of metastatic breast cancer
  • Stable or increasing levels indicate tumor is not responding to the therapy
  • Increasing levels mean recurrence of the disease
  • Higher levels means more advanced disease
  • Very high levels indicate metastases to liver or bones

False positivity is seen

  • During the initial 4-6 weeks of the chemotherapy, this temporary rise does not mean disease progression
  • Benign conditions like
    • Liver cirrhosis
    • Tuberculosis
    • Benign breast cancer
    • Endometriosis
    • Pelvic inflammatory disease
    • Systemic lupus erythematosus
    • Sarcoidosis
    • Pregnancy & during lactation
  • Malignant conditions like
    • Lung cancer
    • Liver cancer
    • Colon cancer
    • Pancreatic cancer
    • Endometrial cancer
    • Ovarian cancer
Other Tests
  • CA 27.29
    • It is a specialized blood test carried out to predict early recurrence of carcinoma of breast
    • High levels indicate recurrence of breast carcinoma
  • HER2/neu
    • It is a specialized blood test carried out for evaluating response of chemotherapy to treat breast cancer
    • It is also carried out using breast tissue biopsy
    • Positive results indicate aggressive tumor, which won’t respond to hormonal therapy or standard chemotherapy, but will respond to trastuzumab drug
  • Estrogen receptor (ER) and progesterone receptor (PR)
    • It is a specialized test that is carried out by tumor biopsy
    • Positive test for ER & PR indicate better prognosis to endocrine therapy
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