Assessment method
  1. Pathology laboratories enrolled in the scheme participate in an assessment run by staining slides circulated from QC mark. The laboratories can only obtain unstained slides from QC mark after electronic submission of relevant protocols before the deadline, filling out the relevant protocol form on www.QC -> Participation. Protocols sent via e-mail or letter are NOT accepted. Only one protocol is accepted for each marker/epitope. If a laboratory submits a second protocol for the same test (e.g., because of corrections), it automatically overwrites the first. When protocol data are submitted, the system gives a receipt (see figure) indicating that the data has been successfully sent (1). Print the data (2) and keep as documentation for your submission.
  2. Only the stains listed at a particular run can be submitted for assessment. If a laboratory does not stock an antibody needed for the detection of an epitope, it cannot be replaced by another antibody. This is due to the design of multitissue blocks and the need for a large number of comparable stains in order to make a proper assessment. For the same reason, stains are not assessed if inappropriate (irrelevant) antibodies have been used.
  3. The sections circulated are serial sections cut from multitissue blocks containing several anonymized normal and tumour tissues fixed in 10% neutral buffered formalin and embedded in paraffin.
    QC mark only sends out medical glass slides with fixed tissue. It is certified that this material is non-hazardous, non-contagious and non-infectious, and is of no commercial value.
    For each epitope two (and only two) unstained sections are sent to laboratories, which have submitted protocols before the announced deadline. Together with the slides, basic information (tissues included, deadline for submission etc.) is provided. Unstained slides are sent at the date indicated on the Participation page.
  4. Laboratories are requested to stain the slides using their standard protocol. One (and only one) slide for each epitope should be submitted to QC mark for assessment together with the in-house control slide. The other QC mark slide should be kept in the laboratory as a reference (or as a reserve in case of a staining failure). In case slides are broken at the receipt, QC mark should be contacted by e-mail.
  5. All stained slides returned to QC mark are assessed and marked by the assessor. Generally, the assessment is based on the staining intensity and distribution in cells expected to stain, background staining, signs of cross-reactivity, counter-staining and tissue preservation during the staining process. Detailed criteria are indicated on the assessment page for each marker. The control stains are not assessed. However, they are requested in order to interpret insufficient stains and – in the future – also to guide the selection of controls.
  6. Submitted stains (including control stains) are stored in the QC mark file for future documentation. The laboratories may request the stains for review – but they must be returned to QC mark. For each such request a nominal charge of Rs. 500 should be paid online. This is to take care of the logistics expenses.
  7. Examples of optimal and suboptimal staining results are uploaded on the website as of the date indicated on the Participation page. Among protocols giving an optimal staining, 2-4 are presented as recommended protocols. They are selected to reflect a spectrum of antibodies and methods and to represent different participating laboratories. The names and e-mail addresses of laboratories providing optimal protocols are given in the protocols to encourage direct communication between laboratories. If a participant providing a protocol wish to remain anonymous, this should be specified in the Comments field. Suboptimal stains are presented anonymously with indication of possible problems or errors in the protocols.
  8. The QC mark lab informs all participants about their individual scores via web upload. The participants are supposed to login and view their results. In case of a borderline or poor staining result, suggestions for protocol optimization are given. In some cases comments are given also to good stains, e.g., in case of excessive counter-stain.
  9. The laboratory should compare their stains and protocols with the optimal stains and recommended protocols published at www.QC A protocol recommended by QC mark as well as changes suggested by the assessment have to be tested carefully in the individual laboratory before implementation into the diagnostic work. QC mark cannot take any responsibility for the consequences of changes in protocols or methods in a laboratory.
  10. Laboratory proficiency tests in QC mark are restricted to the runs. Due to limitations in staff and material it is not possible for laboratories to obtain individual tests outside the runs.
Provided the use of an appropriate antibody, each stain is marked as optimal, good, borderline or poor.

  • Optimal Staining: The staining is considered perfect or close to perfect in all of the included tissues.
  • Good Staining: The staining is considered fully acceptable in all of the included tissues. However, the protocol may be optimized to ensure the best staining intensity and signal-to-noise ratio.
  • Borderline staining: The staining is considered insufficient, e.g., because of a generally too weak staining or a false negative staining of one of the included tissues, or a false positive staining reaction. The protocol should be optimized.
  • Poor staining: The staining is considered very insufficient e.g., because of false negative staining of several of the included tissues, or a marked false positive staining reaction. An optimization of the protocol is urgently needed.

Moderate or strong false positive staining due to, e.g., endogenous biotin is not compatible with an optimal staining.

In case of borderline or poor marks ONLY, the laboratory may request an immediate reassessment of the original stain, or a later reassessment based on a new stain in a following run.
Reassessment of the original stain: If a participant disagrees with borderline or poor marks given, or wishes a more elaborate motivation, a request should be e-mailed to QC mark. The stain will then be reanalysed within 2-3 weeks to make sure that no error has happened and supplementary documentation for the marks provided.
Reassessment based on a new stain: If a participant wishes to document improvement, e.g., after correcting an error or changing the protocol, two new unstained sections may be obtained from QC mark for a new staining in the following (impending) run. Additional charge for logistics shall be paid (appx. Rs. 500 per marker). However, due to the overlap between the first and second annual run in the general module, reassessments from the first run will be carried out in the third run.
For example; reassessment for Run 1 will be offered in Run 3.
To obtain new unstained slides, the participant must fill out a new protocol form before the deadline for the run in which the reassessment is carried out. The new slides are sent together with the slides for the next run and the stains will be included for assessing at the assessor meeting. Due to limited capacity, reassessment can only be carried out once per test and only for tests included in the latest accomplished run.
If the test is already included in the following run (e.g., HER-2), reassessment based on a new stain cannot be requested.