The nearly identical rate of survival between treated and untreated patients with papillary thyroid cancer may indicate that not all cancers need treatment or even detection, according to a new study by Dartmouth researchers Louise Davies and Gilbert Welch.
“Small abnormalities that meet the pathological definition of cancer often tend not to cause health problems in human beings,” Welch said in an interview. “There is a growing body of evidence that suggests that this is a diagnosis we’re making too often.”
When doctors aggressively search for cancer using sophisticated imaging techniques, they find and treat cancers highly unlikely to result in death, according to Welch.
Papillary thyroid cancer is both the most common and most treatable form of thyroid cancer, Welch said. When a malignant thyroid tumor threatens to affect other areas of the body, doctors can surgically remove the thyroid, he said.
In the study, 440 of the 35,663 participants whose papillary cancers had not spread to their lymph nodes did not undergo immediate treatment. Six of these 440 patients died within the six to seven years of follow up treatment, which was comparable to the 161 deaths seen in the treated 35,223 patients, according to the study.
The 2-percent statistical difference in survival rates between treated and untreated patients raises concerns about the necessity of diagnosing and treating non-symptomatic papillary thyroid cancer, according to the researchers.
The question is not whether to treat cancer, “but if we should even be looking for cancer in the first place,” Welch said.
Davies agreed, stressing that truly dangerous cancers would present themselves through symptoms.
“It’s a question of listening to your body,” she said in an interview.
The focus on constant cancer screenings can burden patients with invasive surgeries and complex treatments that they probably do not need to live a long and full life, Davies said.
Detecting cancer early can artificially prolong survival rates not because of the effectiveness of treatment, but because the time spent living with knowledge of the cancer is greater, she said.
Not all physicians agree with Welch and Davies’s interpretation of the findings, Davies said, adding that some colleagues find it impossible to deliberately ignore a tumor.
In an editorial published with the study, Erich Sturgis and Steven Sherman of U. Texas pointed out that while the survival rate might be very similar statistically, even a small difference could mean the loss of a human life. While some patients might need observation rather than immediate treatment, these patients are rare and should be selected with caution, they wrote.
As a counterpoint to the editorial, Welch noted the risks inherent in surgery and treatment, such as the permanent loss of vocal capacity.
Given the emotional nature of the issue, Welch said he hoped the study would be a “wake-up call” challenging “the assumption that everything called cancer is bad and must be treated.”
Davies acknowledged that the decision to observe or treat immediately is difficult and complex. She said, however, she believes that decisions must be made by informed patients and doctors working together, not by medical convention.
“My hope is that by publishing studies like this, it gives people the data they need to have a real conversation with their doctor,” Davies said. “It can be difficult to work with that one person instead of the textbook case, but as physicians, that one person is your job.”
In a similar study published online by the Journal of the National Cancer Institute on April 22, Welch and DMS professor William Black found that premature detection can lead to an overdiagnosis of cancer, which often causes patients to undergo unnecessary and potentially harmful treatments. That study also found that overdiagnosis contributes to escalating health care costs and harms patients prescribed aggressive treatments, The Dartmouth previously reported.