Assessments

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 mark.org -> 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. The laboratories can send coated slides so that tissue peeling can be avoided, though the program takes utmost care in providing sections on best quality coated slides.
5. 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.
6. 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.
7. From Run 16 onwards, the submitted sections are digitally scanned and the link is provided to the participant for dynamic review. The assessors would annotate the area of concern when required. Participants can use these images for learning, education, internal discussions and also raising the doubts by annotating the area.
8. 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.
9. The QC mark lab informs all participants about their individual scores via web upload or individual email. 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 when possible. In some cases comments are given also to good stains, e.g., in case of excessive counter-stain.
10. The laboratory should compare their stains and protocols with the optimal stains and recommended protocols published at www.QC mark.org. 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.
11. 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.

Reassessment run have been suspended as of now.