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Should precursors to breast cancer be treated right away?

Mammogram
Written by Paul Taylor

Question: I have been diagnosed with a breast condition called ductal carcinoma in situ. My doctor says it could turn into breast cancer and should be removed. I did a search online and learned that researchers are doing studies where they don’t immediately operate on this condition. Instead, they take a wait-and-see approach. Only if it progresses will they then cut it out. Is it safe to wait?

Answer: Both doctors and patients have traditionally believed that cancers and pre-cancerous growths should be treated once they are discovered. It was felt that prompt action would greatly reduce the risk of the condition spreading and ending the patient’s life.

In recent years, however, research has suggested that not all cancers or early-stage lesions will become life threatening. Some are so slow growing that the patient will likely die of another cause – such as heart disease – before the cancer turns lethal. This means some patients may have had aggressive cancer treatments that weren’t really necessary.

So, some experts have been advocating the idea of “watchful waiting” or “active surveillance” for a few types of slow-growing cancers and pre-cancerous growths. The patient is closely followed and treatment is started only when the condition appears to be changing. This approach is fairly well established for prostate cancer. Some men enrolled in active-surveillance studies have been followed safely for more than two decades.

Now researchers are starting to explore this strategy with ductal carcinoma in situ, or DCIS – abnormal growth of cells in the breast.

DCIS is sometime called “stage zero” breast cancer, says Dr. Frances Wright, a surgical oncologist at Sunnybrook Health Sciences Centre in Toronto. It’s essentially a “precursor” to cancer.

The abnormal cells are confined to the lining of the milk ducts leading to the nipple. The cells have not spread, or invaded, into the surrounding breast tissue – although they may do so later on. At this point, they are still considered non-invasive and therefore non-lethal.

The standard treatment for DCIS is to surgically remove the abnormal cells. The affected part of a duct may be just a few centimetres in length – or much longer. Depending on the extent of the DCIS, the patient receives either a lumpectomy (part of the breast is removed), or a mastectomy (the entire breast is removed). If a lumpectomy is done, the breast usually also receives radiation therapy to reduce the chance of DCIS coming back.

With the introduction of breast cancer screening programs several decades ago, it has become increasingly common for doctors to detect DCIS.

DCIS now represents about 25 per cent of all breast cancer-related abnormalities identified in mammogram tests. Yet only 30 to 40 percent of these cases will go on to become invasive cancers, says Dr. Wright.

“We are finding tumours that may never cause any problems,” she explains. “And we are putting people through a lot of treatment which may or may not be beneficial to them.”

The challenge is that doctors can’t say with certainty which DCIS cases will advance further. But they have some clues, says Dr. Ralph George, a surgical oncologist at St. Michael’s Hospital in Toronto.

He notes that DCIS tends to become aggressive in younger women. DCIS can also be “graded” by examining a biopsy sample under a microscope, explains Dr. George. When the nuclei of the cells contain lots of abnormalities, the DCIS is rated as “high” grade, with an elevated likelihood it will become invasive.

There are three separate studies currently underway – in Britain (the LORIS trial), Europe (LORD) and the United States (COMET) – to determine if it’s safe and effective to use active surveillance in patients considered to be at low risk of their DCIS spreading, such as older women with low or intermediate grade DCIS.

Some Canadian doctors are hoping to enroll their own patients in these trials. “We have been in contact with the organizers of the British trial and they are very keen to have international participation,” says Dr. Nicole Look Hong, a surgical oncologist at Sunnybrook.

It’s also worth noting that other researchers are reviewing the use of radiation therapy after surgery. They believe certain genetic risk factors may help identify patients who can forgo this part of the treatment.

Hopefully, the trials will provide some answers. “We don’t even know what’s the best way to monitor these patients,” says Dr. Look Hong. In particular, research needs to determine how often follow-up mammograms, ultrasound scans or biopsies should be done to ensure that “any dynamic changes in the cancer are seen promptly.”

Equally important, the findings will have to convince more people that it’s safe to hold off surgery until it’s clearly necessary. After all, when it comes to cancer, most people – physicians and patients alike – are “risk averse” says Dr. George. Many would rather have a cancer removed than let it remain in the body – even if it’s extremely slow growing.

Evidence gathered from the studies may eventually help change these deeply ingrained attitudes, he adds.

About the author

Paul Taylor

Paul Taylor, Sunnybrook’s Patient Navigation Advisor, provides advice and answers questions from patients and their families, relying heavily on medical and health experts. Email your questions to AskPaul@sunnybrook.ca
and follow me on Twitter @epaultaylor