cancersthatdonotkill

Cancers That Do Not Kill: Prevalent and Usually Treated Aggresively

If doctors look hard enough, they will find abnormalities. The problem has escalated with improved imaging techniques like ultrasound and scans that allow them to find tiny cancers and precancerous lesions that, in another era, were not seen beyond the autopsy table. Many, if not most, are inconsequential, but no test can definitively sort out the minority that merit treatment. A lot of unnecessary aggressive treatment is the unhappy result.

Ambiguous findings are so common that they have been given the somewhat wry name of incidentalomas. The word begins with the breezy sound of something found unexpectedly and ends with an ominous ring of cancer. Incidentalomas are found in the kidney, liver, pancreas, adrenal glands, thyroid gland, lung, breast, and prostate—in other words, any organ that can be imaged.

The detection of incidentalomas has been ruining people’s lives well before there was a word for them. Ever since the introduction of the first cancer screening test—the Pap smear—50 years ago. Cancer screening (by definition, a test given to people without symptoms) frequently reveals a type of cancer or a precancer that would have regressed or remained dormant for an entire lifetime. For every person who benefits from early detection, many more are diagnosed with a cancer they did not need to know about.

Based on the combined results of the mammography screening trials, for example, it is estimated: “For every woman who has had her life prolonged [because breast cancer was found on a screening mammogram], five healthy women who would not have received a breast cancer diagnosis had there not been screening will be converted into cancer patients,” according to Jorgensen and Gotzsche (BMJ, 1/17/04). What the public needs is a medical organization that would serve as counterpoint to the American Cancer Society—one that provides a realistic understanding of cancer and all its uncertainties.

The word incidentaloma is more typically applied to a tiny mass, nodule, or lesion found by chance during a biopsy or an imaging test ordered in response to unrelated symptoms. The dilemma they pose was illustrated recently in a New England Journal of Medicine article by John H. Stone, MD, Johns Hopkins School of Medicine, Baltimore. His patient’s puzzling and diffuse symptoms were finally understood after a full-body CT scan identified a problem in the temporal artery. A biopsy specimen found giant-cell arteritis—not cancer, as he had feared. But the relief felt by doctor and patient alike was immediately overshadowed by an unexpected CT-scan finding in the patient’s abdomen: a “5-mm mass in the posterior right kidney. Cannot exclude renal-cell carcinoma.”

The next step was magnetic resonance imaging that produced a report which was not completely reassuring: “consistent with proteinaceous cyst. Recommended follow-up imaging in six months.” As Dr. Stone put it, “Thus, an incidentaloma ruined the patient’s peace of mind and diverted our focus from the otherwise clear path to health.” The most challenging question facing physicians, he wrote, “regardless of the organ in which incidentalomas are found, is what to do with the small ones—the renal mass smaller than 1.5 cm*, the adrenal lesion smaller than 4 cm, and the pituitary abnormality smaller than 1.0 cm. My patient’s 5-mm [about 1/5 of an inch] renal mass challenges the capabilities of any radiologic test ordered in the hope of definitive reassurance. With a growing number of incidentalomas, what to tell the patient remains unclear.”

Although many incidentalomas are clearly cancer, most would never have become life-threatening or symptomatic had they gone undetected and untreated. This is the take-home message from a recent study published in the Journal of the American Medical Association, entitled, “Increasing Incidence of Thyroid Cancer in the U.S., 1973-2005.” The authors, Louise Davies, MD, and H. Gilbert Welch, MD, found a nearly three-fold increase in the U.S. thyroid cancer incidence in this 32-year time period. Yet death from thyroid cancer has always been—and still is—rare, less than 1,500 deaths annually.

Davies and Welch examined other explanations, such as environmental radiation, but traced the increase instead to the widespread use of ultrasound that began in the 1980s. “While thyroid ultrasound cannot diagnose a thyroid nodule as malignant, it can detect nodules as small as 0.2 cm,” they wrote, noting that the physician’s manual examination could only detect nodules that are larger. Ultrasound examinations used to be done in hospital radiology departments, but now more and more thyroid ultrasound machines can be found in doctor’s offices.

“Fine-needle aspiration biopsy is currently our gold standard because it is more likely to produce definitive information,” said Louise Davies, MD, of the VA Outcomes Group, Department of Veterans Affairs Medical Center, White River Junction, Vermont. But, she explained in a telephone interview, fine-needle aspiration may not provide a clear diagnosis, which means undergoing an operation to get a definitive answer, where half or all of the thyroid gland is removed. The latter operation (thyroidectomy) requires life-long thyroid replacement therapy. “Surgeons may recommend removing the whole gland because of the risks associated with re-operation if the nodule turns out to be cancerous,” said Dr. Davies, a surgeon and lead author of the thyroid cancer study.

Asked what people can do to avoid unnecessary treatment, Davies suggested, “Think one step ahead about what you would do, so that you don’t find yourself down a path toward thyroid removal. Consider what you would do if an ultrasound showed a nodule—would you, for example, rather not know you had one in the first place, or would you want to have it rechecked periodically?” She advises people to consider how the thyroid nodule was found, whether it causes symptoms, or if there is a family history of thyroid cancer.

A second opinion about the decision to undergo a fine-needle aspiration is also a good idea, explained Davies. For second opinions, she had this suggestion for choosing a doctor to consult: “If, for example, an endocrinologist suggested you undergo evaluation, then another endocrinologist, a surgeon or a primary care doctor might be a good choice for a second opinion. In any case, choose a doctor at a hospital, or office different from that of the first-opinion doctor.”

Davies and Welch found that the increasing incidence of thyroid cancer is predominantly due to the increased detection of tiny papillary cancers, the most common type of thyroid cancer, usually symptomless, and the least likely to kill. “An untreated 1 cm or less papillary thyroid cancer has a virtually 100% survival rate,” said Davies. “Most worrisome are medullary and anaplastic thyroid cancers, which usually have symptoms.”

The presence of symptoms is key. “If you have a small lump that you can’t feel, but your doctor can, and yet you have no symptoms—that’s an incidentaloma. People should realize if they don’t have symptoms, they have time to wait three to six months to have it evaluated. With incidentalomas, that’s key,” said Davies. “Early detection of an incidentaloma doesn’t necessarily lead to a longer life. Instead, it may just lead to a longer period of time in which you know you have cancer.”

*2.5 cm or 25 mm = 1 inch

How Prevalent is Cancer? How Prevalent are Cancers That Kill?

The following statistics are based either on autopsy studies of people not known to have cancer during their lifetime or ultrasound examination studies of symptom-free people. They show that the prevalence of many cancers—and would-be cancers—is well in excess of cancer diagnosed in the living population. The U.S. cancer death statistics come from the American Cancer Society.

Thyroid:

An ultrasound screening study of 96,278 people found thyroid nodules present in 35% of women age 26 to 35, increasing to nearly 45% of women aged 55 and over. Thyroid nodules were present in 9% of men ages 26 to 35 and increased to 32% in men aged 55 and over.

Several autopsy studies have found that thyroid cancer is present in 36% of all people. In one of these studies, researchers examined extremely thin slices of the thyroid glands of 101 people and found many more, smaller (2-3 mm) thyroid cancers in the slices. This led them to conclude that, if sliced finely enough, virtually everyone’s thyroid would be found to have cancer.

An estimated 1,460 people will die of thyroid cancer in 2006.

Adrenal gland:

Autopsy studies found adrenal masses, 2 mm to 4 cm, in diameter to be present in approximately 10% of people.

Approximately 1 out of every 4,000 adrenal tumors is malignant. Deaths from adrenal cancer are so rare that the ACS does not provide a number.

Kidney:

An ultrasound study of the urinary tract of 729 people found the prevalence of kidney cysts was 1.7% in those aged 30-49 years, 11.5% in those aged 50-70 years, and 22% in those aged 70 years and older.

An estimated 12,480 people will die of kidney and renal pelvis cancer in 2006.

Prostate:

Autopsy studies indicate the presence of prostate cancer in men is 10-42% at age 50-59 years, 17-38% at age 60-69 years, 25-66% at age 70-79 years, and 18-100% at age 80 years and older.

There were 30, 350 prostate cancer deaths in 2005.

Breast:

Autopsy studies show the prevalence of ductal carcinoma in situ, a tiny non-invasive cancer within the milk duct, is 6-16%. Prior to the introduction of mammography screening, this diagnosis represented less than 5% of all new cases of breast cancer, now it is 20%. Since most cases of DCIS are treated with either breast removal or radiation, it is not known how many would have regressed or remained dormant without treatment. However, 78 women whose biopsied tissue was mistakenly diagnosed as benign in the pre-mammography era provided an opportunity for researchers. They did a followup study and found that only 20-25% of these untreated women went on to develop invasive cancer ten years after the biopsy. Some breast cancer researchers believe that the DCIS diagnosed today with improved imaging techniques is even more likely to be inconsequential than these 78 cases indicate.

Evidence that some invasive breast cancers found “early” on a screening mammogram do not always progress to be life-threatening comes from the National Breast Screening Study of Canada. Over 50,000 women in their 40s were randomly assigned to have mammograms or not. 82 more breast cancers were detected in the women given mammograms. (592 invasive and 71 non-invasive breast cancers in the mammography group, compared to 552 invasive and 29 noninvasive breast cancers in the control group.) One would expect a higher survival in the mammography group with its higher rate of cancer detection. But, in fact, the breast cancer death rate in both groups was exactly the same at 16 years.

There were 40,410 breast cancer deaths in 2005.