When you learn you have cancer, you want to know what to expect: How will doctors treat your illness? How effective is treatment likely to be?
Much depends on the way doctors first classify, or “stage,” your cancer, using the official staging manual from the American Joint Committee on Cancer. Staging guidelines continue to evolve as knowledge about individual tumor growth and innovative technologies come into play.
An ever-evolving system
“Historically, we staged cancers according to tumor size, lymph node involvement and the presence of metastases,” says oncologist Dale Shepard, MD, PhD.
“The latest staging manual incorporates new findings on the importance of changes in molecular DNA and tumor genomic profiling. This will affect many patients going forward.”
Among those most impacted by changes in staging are people newly diagnosed with breast cancer; head and neck cancer caused by human papillomavirus (HPV); or sarcoma.
How staging works
“Staging allows us to stratify patients into groups based on anatomic and other criteria. It gives us a framework for understanding the extent of disease,” Dr. Shepard explains.
Cancers are staged clinically and pathologically:
- The clinical stage is determined during the initial workup for cancer.
- The pathologic stage is determined by studying a surgically removed tumor sample under the microscope.
Adds Tumor Registry Manager Kate Tullio, MPH, MS, “Staging helps physicians and other researchers to compare patients with the same types of cancer to each other in a consistent way — so that we might learn more about these cancers and how to effectively treat them.”
Staging allows doctors to determine the best course of treatment for different types of cancer and helps families to understand the prognosis, or likely outcome, of that treatment.
It also allows doctors to offer patients a chance to participate in clinical trials of new therapies targeting their form of cancer.
The impact of DNA changes on breast cancer
In the past, most breast cancer patients with lymph node involvement were automatically classified as stage II or higher, and were often given chemotherapy.
“Previously, physicians considered only tumor size, lymph node involvement and spread of the cancer to distant areas of the body when staging breast cancer,” says Ms. Tullio.
Today, staging has improved with the addition of advanced multi-gene panel testing and specific information on the biology of the tumor.
“This incorporates what we have found clinically: that some patients previously identified with stage II breast cancer did better than others,” says Dr. Shepard. “In essence, patients with HER2-positive disease were more like patients with stage I disease.”
HPV’s effect on head and neck cancers
The classification of head and neck tumors has changed because of advances in genomic profiling.
“We now have a separate system for classifying head and neck cancer caused by HPV infection because we realize that, clinically, it is a different disease,” says Dr. Shepard.
Ms. Tullio notes that patients with head and neck cancers caused by HPV have a better prognosis — living longer, on average, than head and neck cancer patients without HPV.
“Patients with HPV-positive mouth or throat cancers usually respond well to treatment and may need less aggressive therapy than those who are HPV-negative,” she says.
Also new, adds Dr. Shepard, are separate classification systems for soft-tissue cancers called sarcomas. Doctors have found that, based on the primary tumor’s location, sarcomas will behave and respond to treatment differently.
How will these changes affect you?
The impact of these staging changes will be far greater for patients with cancers diagnosed on or after Jan. 1, 2018.
“If your cancer is new, then changes in classification may affect early decisions about your initial care and likely prognosis,” says Dr. Shepard.
If you received a cancer diagnosis before that date, the stage of your tumor will not change, Ms. Tullio notes. However, new data in the manual may allow your doctors to better assess and treat you.
Adds Dr. Shepard, “Talk to your doctor if you have any questions about the new staging systems. It’s important to be sure all the right tests are ordered to accurately assess your cancer.”