Revolutionizing Cancer Detection: The Role of Advanced Screening Markers

Screening and Early Detection Markers in Cancer Diagnosis

William Bigbee, PhD and Ronald B. Herberman, MD.

Cancer screening markers are diagnostic tools designed to identify asymptomatic individuals at risk of developing cancer. The primary goal of employing these markers is to detect malignancy or its precursors early enough for effective therapeutic interventions. Since the application targets healthy people without symptoms, an ideal marker must be non-invasive, cost-effective, and robust enough for population-wide testing. Sensitivity, typically high when screening individuals who already have cancer true positive rate, is a key performance metric; however, the defining characteristic of an optimal screening test is its specificity, particularly very low false-positive rates indicating the proportion of healthy individuals incorrectly identified as having disease.

Non-binary markers are quantified on a continuous scale and require setting a threshold for interpretation through Receiver Operating Characteristic ROC analysis. Validation of these markers involves demonstrating their ability to reduce cancer burden in screened populations. However, even if an early detection tool effectively identifies malignancy at the earliest stages, several factors may prevent its overall benefit:

1. Lack of effective treatment options for marker-detected cases.

2. Poor adherence by participants to the screening procedure.

3. Excessive costs or associated health impacts from testing and false-positive results requiring additional diagnostic procedures.

4. Overdiagnosis, where harmless lesions are incorrectly identified as cancer that poses no immediate health risk.

To assess these aspects comprehensively, a well-designed randomized clinical trial is essential, with one arm consisting of screened individuals while the other remns unscreened for comparison.

For instance, to detect a 20 reduction in cause-specific mortality with 80 statistical power requires observing hundreds of deaths across all cohorts, deping on cancer prevalence and mortality rates.

Historically, several screening methods have been effective in reducing mortality:

1. Mammography for breast cancer

2. Papanicolaou test PAP for cervical cancer

3. Fecal occult blood tests combined with flexible sigmoidoscopy or serum carcinoembryonic antigen CEA testing for colorectal cancer

In recent years, immunodiagnostic methods have revolutionized the detection of specific tumor markers in serum:

1. CA125 is a marker for ovarian cancers

2. CEA indicates gastrointestinal malignancies

3. PSA signifies urological cancers

Each of these tests involves measuring proteins produced by tumors that can be detected in blood or other body fluids, enabling early diagnosis and monitoring disease progression.

In , the development of effective screening markers requires not only accurate detection capabilities but also robust evaluation for potential benefits compared to risks. The evolving landscape necessitates continuous research and validation processes to refine existing methods and identify new diagnostic tools capable of improving cancer outcomes.
This article is reproduced from: https://www.ncbi.nlm.nih.gov/books/NBK12673/

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