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Anchoring Bias: Is It Real?

Tania Jain, MBBS
Published: Sunday, Dec 03, 2017
Tania Jain, MBBS
Tania Jain, MBBS
During a typical afternoon, you have a cramped schedule with 8 to 9 patients to see during a 3-hour clinic. Your pager buzzes many times, in between these clinic encounters about another patient receiving chemotherapy under your care. The stage is set you to make a decision for your patient without thinking too much. Alternatively, you may rely too heavily on the information provided by another physician, which is (un)popularly known as “anchoring bias.”

Case 1

An elderly woman was evaluated for new-onset strabismus. A magnetic resonance imaging (MRI) scan of her brain revealed a petrous-caval area lesion, which was reported to be a meningioma based on its radiographic appearance. She also reported worsening back pain. An MRI of her spine revealed a L4 lytic lesion. A biopsy of the vertebral lesion revealed findings of a plasmacytoma—an extramedullary version of monoclonal plasma cell neoplasm that is not related to meningioma in the oncology pedigree.

Initially, I was inclined to accept the radiological diagnosis as it was. After all, it was a busy day like any other and my decisions had to be made in the blink of the eye. However, I was unable to eliminate the ever-nagging question in my head: “What if...?”

After deliberating with the patient about the pros and cons, we decided to obtain a biopsy of the intracranial mass. Ironically, this biopsy revealed a plasmacytoma. This was important. It changed our management plan from focal radiation to the hip and spine for the solitary plasmacytoma to, instead, systemic therapy for multiple plasmacytomas and systemic disease. The long-term benefits have yet to be determined, but we hope and believe that our lastminute dramatic intervention allowed us to make the right decision for the patient.

At first, I didn’t think there was a reason to share this case. However, I was later inspired to share my story after attending a morbidity and mortality case conference during which the case mentioned below (case 2) was discussed.

Case 2

A middle-aged man was evaluated for a metastatic melanoma located in the lung. The man’s brain scan revealed a lesion that was, incidentally, deemed to be a meningioma based on his radiology report. But was it? This time, a lack of time to consider the man’s options for diagnosis got the better of the clinician’s judgment.

The decision was made to start systemic therapy for melanoma while following the brain lesion, as would be done for a meningioma. As we know, intracranial metastasis from melanoma warrants radiation or surgical intervention. Nevertheless, treatment for melanoma was initiated with immunotherapy, a treatment consideration given former President Jimmy Carter’s case. As we have learned, the median time to treatment response is roughly 3 months with immunotherapy.1

As oncologists, we don’t get many shots at being right. After a couple of weeks, the patient developed a change in mental status, which turned out to be secondary to increasing size of the brain lesion and worsening edema surrounding it. Upon surgical resection and microscopic evaluation at this time, the brain lesion was found to be metastatic melanoma, which was then managed with postoperative radiation in addition to systemic therapy.

Case 3

After initially being signed out of the emergency department by his physician as having meningitis, as suggested by a high fever, tachycardia, headaches, and tremors, a patient was admitted to the medicine floor for further care. An additional elaborate patient history, obtained by a medical student on the hospital floor, revealed that the patient had a history of hyperthyroidism. The patient also mentioned that he had not taken his medication for the condition in a while. Fortunately, the medical student was neither shy nor slow to speak up. Based on the results of additional workup, a hyperthyroid crisis was diagnosed, which could have become potentially fatal if not recognized in time and managed appropriately.

Recognizing Anchoring Bias

Anchoring bias refers to a cognitive tendency to lock on to a clinical diagnosis too early, often by making decisions based on information provided by another physician. It’s the tendency to fit the symptom complex into the diagnosis box and anchor onto a diagnosis already provided to us.

Historically, anchoring bias was first conceptualized by professors Amos Tversky, PhD, and Daniel Kahneman, PhD. Anchoring bias is an issue not only recognized by physicians in healthcare, but also in other professions and even in our daily lives. Over the years, psychologists have tried to put together various theories describing the mechanism of this occurrence.2 Regardless of how it happens, it can potentially be catastrophic, although rarely so.


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Online CME Activities
TitleExpiration DateCME Credits
Community Practice Connections™: Oncology Best Practice™ Decision Points in Advanced NSCLC: Assessing Treatment Options Beyond Disease ProgressionNov 30, 20181.0
Community Practice Connections™: Precision Medicine for Community Oncologists: Assessing the Role of Tumor-Testing Technologies in Cancer CareNov 30, 20181.0
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