In the February 1, 2019 issue of American Family Physician , there is an editorial by H. Gilbert Welch titled "." He points out that the incidence of kidney cancer has more than doubled since 1975, but "This is not an epidemic of disease, this is an epidemic of diagnosis." It is a side effect of increased use of imaging. The majority of kidney cancers today are detected as incidental findings on a CT scan ordered for a totally unrelated reason. Areas where more CT scans are done have a higher incidence of nephrectomies.
Diagnoses of kidney cancer are indeed on the rise. It is one of the top ten cancers in the US. , in 2019 we can expect 73,820 new cases of kidney cancer (44,120 in men and 29,700 in women) and 14,770 deaths from the disease (9,820 in men and 4,950 in women). The lifetime risk of developing kidney cancer is 1 in 48 men and 1 in 93 women. It can present with bloody urine, flank pain and an abdominal mass, and 20% of patients present with paraneoplastic disease (hypertension, hypercalcemia, and polycythemia). But more than 50% of patients are asymptomatic at the time of diagnosis. And 30% of patients already have metastases when they are diagnosed. Treatment is usually surgical, but some patients can be followed with active surveillance.
CT can detect 90% of renal masses and can help identify benign masses that do not require further investigation and lesions that can be monitored with active surveillance. The are 93% for localized cancers and 12% if there are distant metastases, so early detection would be expected to save lives. Unfortunately, no screening test has been shown to reduce the risk of death, and screening tests for renal cell carcinoma are not recommended except in the case of certain inherited syndromes.
This graph from the editorial shows that while the incidence of kidney cancer has doubled, there has been no change in mortality or in the incidence of metastases. The 5-year survival rate is increasing, but this is an artifact of .
There is another , not of disease but of overdiagnosis. Screening for thyroid cancer is not recommended in the US, but it has been aggressively pursued in South Korea, where by 2011 the incidence of thyroid cancer diagnoses had risen to 15 times the level in 1993. David Gorski has written about overdiagnosis in Japan following the Fukushima disaster and about the willful misunderstanding of overdiagnosis.
An incidentaloma is an unexpected abnormality accidentally found on medical imaging studies done for an unrelated reason. Estimates vary, but incidental findings of imaging studies. In a TedX talk, radiologist Jill Wruble said she never saw a "normal" patient; she . Researchers are trying to develop guidelines to help clinicians decide whether a given incidental finding requires further evaluation. Meanwhile, patients and doctors worry. Pursuing a diagnosis is likely to require invasive and expensive tests, including biopsies and surgery with all their possible harms and complications, up to and including death. I described how an incidentaloma on a routine (and not medically indicated) chest x-ray started a sequence of events that killed my father-in-law. Scans have detected incidentalomas in my own liver and kidney that my doctors agreed did not warrant any further investigation. I am not worried, but I can imagine how medically naïve patients might worry obsessively about what was lurking in their body, particularly if they distrust the medical profession.