Cervical cancer is said to be a leading cause of cancer-related deaths amongst women in India. In fact, a global survey commissioned and funded by GSK states that every year, more than 72000 women in India die due to cervical cancer. Therefore, the emphasis is on early testing and diagnosis. It has been revealed that pap smear, the most commonly used technique to diagnose cervical cancer has some limitations that includes, more ‘false negative’ rate which cause lot of complications later and when detected can cause costlier medical interventions. However, ThinPrep system which uses liquid based technology to address preparation and screening errors is said to be more effective for the detection of epithelial lesions than conventional pap smear. Mahendra Paranjape, Product Manager – Diagnostics, Trivitron Healthcare speaks about the benefits of ThinPrep over the conventional pap smear, in an interaction with Raelene Kambli
What is ThinPrep technology? How effective is it in detecting cervical cancer?
| Mahendra Paranjape |
With the conventional pap smear, a preparation error can occur when abnormal cells on the collection device do not make it to the slide for diagnostic review. When a clinician prepares a conventional pap smear slide, he or she literally “smears” the sample onto a slide and discards the collection device. Studies have found that more than 80 per cent of the sample can be discarded with the device. The portion of the sample that does make it to the slide is a non-representative sub-sample, meaning the clinician has no control over which cells make it to the slide and which do not. Existing cervical cell abnormalities may be on the collection device after the sample is collected from the patient but may never make it onto the slide for diagnostic review.
With the ThinPrep system, a doctor collects a sample in the same way he or she would for a conventional test, but then rinses the collection device in a vial of proprietary preservative solution. The ThinPrep pap test addresses preparation errors because virtually all of the cervical cells collected from the patient are then collected in the vial, which is sent to the lab for slide preparation. The slide, containing a representative sub-sample of cells, is prepared at the laboratory for diagnostic review.
At the lab, the ThinPrep system addresses screening errors, another cause of false negatives. Using the conventional method, a doctor smears the sample collected from the patient onto a slide. This sample is commonly clouded with mucus and debris. This, combined with a slide containing cells that are overlapping and clumped together, results in a slide that is exceptionally difficult to read. With the ThinPrep system, the physician needs only to send the vial containing the cell sample to the lab. At the lab, a clear, easy to-read slide sample that displays a thin layer of evenly distributed cells is produced.
So can you list down the reasons why ThinPrep technology should be chosen over the conventional pap smear method ?
a) Decrease in sampling error—In conventional pap testing
- Cells are not collected properly,
- Cells are not transferred on slide completely,
- Cells are not preserved completely leading to drying artefacts.
All these are avoided in ThinPrep pap test thereby causing higher cell yield– as more than 80 per cent cells are discarded in conventional technique.
b) Decrease in transportation errors—Slide breakage is avoided, mislabelling is minimised.
c) Decrease in screening errors—False negative rate is minimised. Diagnostic accuracy is far more than the conventional.
d) Decrease in interpretative errors—Due to excellent fixation of cells, interpretation is made very easy leading to decrease in repeat pap smear testing. No ambiguous reports.
e) Decrease in inadequacy/ unsatisfactory rate.
f) Decrease in limiting factors like blood mucous, inflammation etc.
g) Additional testing of HPV is possible in same vial. No need to collect another sample thereby decrease patient trauma.
h) Glandular disease detection rate is superior
How effective is this technique in detecting cancers in high-risk patients?
The ThinPrep pap test has FDA-approved labelling that states it is “significantly more effective than the conventional pap smear for the detection of low-grade squamous intraepithelial (LSIL) and more severe lesions in a variety of patient populations,” thereby increasing the opportunity to detect and treat these types of cervical abnormalities.
Is this technique new in India?
The technique is not new in India as ThinPrep was available in India from 2009. Day-by-day the awareness is increasing and more cytology labs as well as gynaecologists are referring to LBC- Thin Prep.
How many physicians in India use this technique to detect cancer?
The technology LBC on ThinPrep system is used by more than 20 customers (cytology/ histopathology labs) and they are getting the samples from physicians. It will be difficult to give numbers.
Are there any precautions that physicians need to follow while using this technique?
There is no such precautions to be taken by physicians and they found that the sample collection procedure very easy.