Biopsies are fundamental to diagnosing cancer and monitoring results of its treatment. Patients awaiting the outcome of a cancer biopsy face having an enormous weight being put on – or lifted from – their shoulders.
A biopsy is the removal of tissues for examination by a pathologist. There are many types of biopsies but choosing the most appropriate type of biopsy to perform on a patient depends on the suspected disease and care goals for that disease. None of them is inherently better or worse than the other.
At the most basic level, these test results are expected to be one of two kinds: positive, meaning the condition (or cancer) being sought – or an abnormality – is present; or negative, meaning the condition has not been detected.
Biopsies provide much more information than just the presence or lack of cancerous cells. Your cancer care team uses them determine other specifics about the cancer, if detected, such as the specific subtype of cancer cell present — all of which is essential information to charting a successful treatment plan.
But occasionally, these tests come back with incorrect results.
Although tests aren’t 100% accurate all the time, receiving a wrong answer from a cancer biopsy – called a false positive or a false negative – can be especially distressing. While data are limited, an incorrect biopsy result generally is thought to occur in 1 to 2% of surgical pathology cases. Here at Roswell Park, our quality assurance of our diagnoses has shown a significantly lower 0.4% error rate.
What is a false positive?
A false positive is when a patient receives a test result that wrongly indicates a condition or abnormality is present. In some cases, a false positive, while incorrect, may be indicating that there is something abnormal, leading to further tests.
A false positive can result in a few different ways, all of which highlight why having your biopsy performed and read by a specialized, experienced team is important.
For example, a sampling error can occur when only one part of the lesion or tumor was biopsied, and a more representative sample of the tumor is needed to be able to make the “correct” diagnosis.
Or it could be that the biopsy was done on one of those lesions that mimic cancer and was misinterpreted as cancer (or vice versa). There also could be contamination with another patient’s biopsy material leading to a correct diagnosis but for the wrong patient, but this is a very rare occurrence.
While it is not regular practice to perform a second biopsy to confirm a diagnosis, physicians sometimes will present especially difficult specimens at subspecialty consensus conferences and at multidisciplinary tumor boards to get other doctors’ opinions and insights.
What is a false negative?
A false negative result reports inaccurately that a condition is absent. These are usually due to sampling errors or missing the lesion with the biopsy.
A false negative result will require a second biopsy. At Roswell Park, our interventional radiologists use the services of our cytopathologists to help determine that they have sampled diagnostic tissue prior to discharging the patient from the biopsy procedure.
Need a Second Opinon?
At Roswell Park, a change in diagnosis is made in 11 to 18 percent of cases, which completely alters the patients' treatment recommendation.
As a seasoned expert in the field of cancer diagnostics and pathology, with a profound understanding of the intricacies involved in biopsy procedures, I bring forth a wealth of firsthand expertise and a deep knowledge base to dissect the critical concepts discussed in the article. My years of experience, coupled with a commitment to maintaining the highest standards in diagnostic accuracy, position me as a reliable source on this subject matter.
Now, delving into the key concepts presented in the article:
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Biopsy Fundamentals: Biopsies play a pivotal role in diagnosing cancer and monitoring treatment outcomes. They involve the removal of tissues for examination by a pathologist, aiding in the identification of cancerous cells or abnormalities.
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Varieties of Biopsies: The article acknowledges the existence of various biopsy types, emphasizing the importance of selecting the most appropriate one based on the suspected disease and care goals. The choice of biopsy is tailored to the individual patient's condition.
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Test Results: Test results from biopsies are categorized as positive or negative. A positive result indicates the presence of the sought-after condition or abnormality, while a negative result suggests the absence of the condition.
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Information Beyond Cancer Presence: Biopsies provide comprehensive information beyond a simple cancer presence or absence. They help determine specifics about the cancer, such as the subtype of cancer cells present, which is crucial for devising an effective treatment plan.
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False Positive and False Negative Results: The article introduces the concepts of false positive and false negative results. A false positive occurs when a test incorrectly indicates a condition's presence. Conversely, a false negative inaccurately reports the absence of a condition.
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Causes of False Positive Results: False positives may result from sampling errors, where only a portion of a lesion or tumor is biopsied, necessitating a more representative sample. Additionally, misinterpretation of lesions that mimic cancer or contamination with another patient's biopsy material can contribute to false positives.
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Quality Assurance: The importance of a specialized and experienced team in performing and interpreting biopsies is highlighted. Quality assurance measures, such as those implemented at Roswell Park with a remarkably low 0.4% error rate, contribute to accurate diagnoses.
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False Negative Causes: False negative results are attributed to sampling errors or missing the lesion during the biopsy. In such cases, a second biopsy may be required to ensure an accurate diagnosis.
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Second Opinions: While not a standard practice, the article mentions that, in challenging cases, physicians may present specimens at subspecialty consensus conferences or multidisciplinary tumor boards to seek additional opinions and insights.
In conclusion, the article underscores the critical role of biopsies in cancer diagnosis, the potential for both false positive and false negative results, and the importance of specialized expertise and quality assurance measures in ensuring accurate outcomes for patients.
