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Repeated Ki67 and result is shocking

my first ki-67 is + in 35% of the cells

I had to change hospital because my first hospital refused to give treatment and suggested just surveillance

The second hospital asked to repeat the test on all the tissue and all the results were pretty similar except for ki-67

Second test Ki-67 is + in 90% of the cells

I am so confused is that possible can the result vary this much between labs?
there is only 2 weeks difference between tests

Which one is right which one is wrong?
will this differ in the treatment plan?

My diagnosis is

  • Extensive high grade DCIS
  • IDC 3 foci greatest 3mm
  • Grade 3
  • ER, PR Negative
  • HER2 + score 3
  • pT1a, N0

i am 30 years old and my treatment plan is paclitaxel 12 weeks every week, trastuzumab 1 year every 3 weeks

Comments

  • exbrnxgrl
    exbrnxgrl Member Posts: 5,220
    edited September 21

    Ki-67 comes with some controversy regarding its usefulness. Many oncologists do not measure it at all, or take it with a grain of salt. Although it’s good that you’re asking about it, it’s significance isn’t entirely clear. The following is from an ASCO publication:

    Challenges and Controversies of Ki-67 as a Prognostic Marker

    Despite clear data for Ki-67 as a prognostic marker in early-stage breast cancer, its importance in determining therapy in routine adjuvant treatment of breast cancer is uncertain for several reasons. First, differences in standardized IHC assays and analytical method and a lack of precise cutoff have made clinical use of Ki-67 controversial.5,6,11 One of the challenges around Ki-67 is the wide variability in testing across laboratories revolving around choice of primary antibody, counting methods, and staining differences.3,6 Certain tumor features, such as tubule formation, inflammatory cell infiltrates, low cellularity, and nuclear grade, can also hinder proper analysis for both artificial intelligence models and pathologists and require careful assessment by an experienced pathologist.6 Additionally, reliability of Ki-67 assessment by IHC is also questionable because of interobserver variability and intratumor heterogeneity.6,15 Although the International Ki-67 in Breast Cancer Working Group (IKWG) has established a standard protocol for Ki-67 testing, adoption is lagging, with many local institutions not running the Ki-67 at all.6 Hospitals that do the testing may not be using the FDA-approved assay. If the sample is sent for central Ki-67 testing, additional costs may be billed to insurance or to the patient and care may be delayed. -ASCO Daily News January 2023