Breast cancer staging has changed
Cape Cod Hospital oncologist Jennifer Crook, MD, carries her new 1,000-page eighth edition of the American Joint Committee on Cancer (AJCC) Staging Manual: Breast Cancer to every cancer conference she attends in her department. It is in these conferences that Cape Cod Hospital oncologists discuss staging and treatment options for their cancer patients.
“Some of the staging is easier than others, but when you get down to subtleties, especially in early stage cancer, we pull out the book,” she said.
The new guidelines, which took effect in January 2018, change the way breast cancer is staged by using the most up-to-date algorithms, including genomic testing (oncotype).
Genomic testing gives much more information about how the cancer will behave and if it will respond to treatment, according to breastcancer.org.
“The new system is very complicated,” said Dr. Crook, holding her thick book, filled with sticky note- flagged pages.
While the guidelines now include broader and more detailed information on risk of recurrence and how to decide chemotherapy or hormonal treatment after surgery, the old system of assessment is still in place. The traditional system is called the TNM system, according to Dr. Crook.
What Is TNM?
“TNM” refers to the following, according to the National Cancer Institute:
- T - refers to the size and location of the main tumor.
- N - refers to the nearby lymph nodes that may contain cancer.
- M - refers to whether or not the cancer has metastasized (spread) to other parts of the body.
With the information gathered from the TNM system and the new algorithms, oncologists can modify or further classify the staging based on the risk predictors they get from genomic testing, said Dr. Crook.
“The size of the tumor can sometimes be misleading,” said Dr. Crook. “Someone can have a very big tumor that doesn’t act aggressively and they may do great. Yet someone with a very small tumor that doesn’t look harmful because of its size, recurs two years down the road.
“That’s where genomic testing is helping us. It’s looking at a number of different genes within the tumor and their processes to tell us how the tumor is going to act. It classifies those we have to worry about and those we don’t, independent of the size criteria.”
Other considerations include whether a tumor has estrogen receptors (ER) or progesterone receptors(PR) which, if present, need estrogen and progesterone to grow. The cancer can be treated with hormonal therapy to inhibit or prevent their growth. Human epidermal growth factor receptor 2 (HER2) is a protein on the outside of breast cells that also promotes growth of cancer cells. When these levels are elevated, the cancers tend to grow faster and spread and require a more targeted therapy.
Differences in staging systems
The biggest difference from the old staging system and the new one is there are a number of women who would be classified as having Stage II breast cancer, according to Dr. Crook.
“When they have the genomic (oncotype) testing and their results are a good risk or low risk, we can downstage them to Stage I. Even though they meet the TNM criteria for stage II, the good risk genomic testing outweighs the old results. It’s very nice,” she said.
The other important change is the classification of lobular cancer in situ (LCIS), she added. LCIS is less common than ductal carcinoma in situ (DCIS) and in this new staging paradigm, it has been removed. LCIS is no longer considered cancer and is referred to as a pre-malignant lesion. DCIS is still considered Stage 0 cancer, she said.
In order to provide the latest care, Dr. Crook will continue to carry her manual to the cancer conferences, where individual cases are discussed – and treatment suggested - by a multi-disciplinary group of clinicians.