Wait, Cancer Has a Stage 0?

Most people have heard of cancer stages 1 through 4, but not everyone has heard of stage 0 cancer. Cancer stages represent the extent to which the disease has progressed. For decades, the TNM Classification of Malignant Tumors has been the global standard for cancer staging. This system categorizes solid tumors based on their size (T), lymph node involvement (N), and whether the cancer has metastasized (M).

Traditionally, the TNM system has relied on visible symptoms, which often appear after cancer cells have spread. But with advances in medical imaging and screening technologies, doctors can now detect abnormal cells before they become invasive. This breakthrough has led to the identification of carcinoma in situ, which translates from Latin as “cancer in place” or stage 0 cancer.

What is stage 0 cancer?

Stage 0 cancer is the earliest and most localized form of cancer. It is noninvasive, meaning it hasn’t spread to nearby tissues. Because of this, stage 0 cancers are highly treatable and often curable, with survival rates approaching 100% in many cases.

“It’s a relatively new concept in cancer staging,” says Chad Ritch, M.D., M.B.A., F.A.C.S., a urologic oncologist at Sylvester Comprehensive Cancer Center. “It’s an early cancer, like a superficial cancer.”

Despite its positive prognosis, stage 0 cancer is relatively rare. Dr. Ritch, also a professor of urologic oncology at the Miller School of Medicine’s Desai Sethi Urology Institute, says the abnormal cells are often too small to form a detectable tumor on internal scans such as MRI or ultrasound.

However, precancerous cells on external tissues — like the skin or cervix — are more easily detected.

Common sites for carcinoma in situ include the bladder, lungs, skin, breasts and cervix. The good news? No matter where it appears, stage 0 cancer is highly treatable when caught early.

Stage 0 bladder cancer’s diagnosis and treatment

In stage 0 bladder cancer, the abnormal cells remain confined to the bladder lining and have not invaded deeper layers. This stage is further divided into two subtypes:

• Stage 0a: Tumors are located in the bladder lumen (where urine collects).
• Stage 0is: Abnormal cells spread across the bladder lining without forming a tumor.

Stage 0is is more concerning because it’s always considered high grade. The cells are more aggressive and more likely to turn into invasive bladder cancer, says Dr. Ritch.

Treatment for stage 0 bladder cancer depends on the subtype:

• Stage 0a: Tumor removal via a minimally invasive procedure, followed by intravesical (instilled in the bladder) chemotherapy.
• Stage 0is: Typically treated with intravesical BCG immunotherapy; intravesical chemotherapy may follow if needed.

The 10-year survival rate is above 90%. However, recurrence is common. “The issue is recurrence, so surveillance is very important,” Dr. Ritch says. “About 30% to 40% of cases return because cancer cells can remain in the bladder lining.”

Stage 0 lung cancer is rare but detectable early

Stage 0 lung cancer is uncommon and often discovered by chance during imaging for unrelated issues. It makes up less than 3% of lung cancer cases, says Estelamari Rodriguez, M.D., M.P.H., a breast and thoracic oncologist with Sylvester.

“It is more frequently found in women, never-smokers, and people of Asian descent,” says Dr. Rodriguez. “It’s often associated with mutations in the EGFR gene.” Mutations in the EGFR gene, often linked to non-small cell lung cancer, lead to uncontrolled cell growth and tumor formation.

These early-stage lesions are often visible as ground-glass opacities on imaging and exhibit a lepidic growth pattern under a microscope, without high-risk signs like pleural invasion.

Treatment for stage 0 lung cancer typically involves surgical resection, the least invasive surgical option. No radiation or chemotherapy is usually needed.

“If the disease is diffuse or unresectable, we monitor patients closely,” Dr. Rodriguez says. “I have patients we’ve followed for years with no major changes.”

Stage 0 breast cancer is the most common in situ cancer

Among all stage 0 cancers, breast cancer is the most frequently diagnosed. Ductal carcinoma in situ (DCIS) accounts for roughly 20% of all new breast cancer cases.

Thanks to regular mammogram screenings and digital imaging advances, more women are being diagnosed before symptoms appear. Digital mammography offers better resolution and sensitivity, says Elisa Krill-Jackson, M.D., a breast medical oncologist at Sylvester.

“We now have an opportunity to catch it before it spreads, which improves the breast cancer survival rate to about 100%,” she says.

Stage 0 breast cancer treatment depends on hormone receptor status and size, often involves a lumpectomy, and is sometimes followed by radiation therapy to reduce recurrence risk. If the cancer is hormone receptor-positive, doctors may recommend anti-estrogen therapy. For some low-risk patients, active surveillance is an option.

Even with excellent outcomes, the word “cancer” triggers emotional distress for most patients.

“Patients are fearful that this means their life is at risk when, in fact, this has been detected before the abnormal cells have escaped the walls of the breast duct and therefore have no opportunity to spread to other parts of the body,” Dr. Krill-Jackson says. “You have to help them understand that, of all potential diagnoses, this is a best-case scenario.”

Dr. Ritch sees similar concerns, especially regarding financial strain. “There’s the stress of the diagnosis and of ongoing surveillance, but bladder cancer is also one of the most expensive cancers to treat,” he says.

Despite these challenges, with appropriate treatment and accurate diagnosis, there should be essentially no risk for life-threatening metastatic disease. “It’s caught early, it’s small, it hasn’t had a chance to spread, and it’s very treatable,” Dr. Krill-Jackson says.

Written by Ana Veciana-Suárez, a regular contributor to the University of Miami Health System. She is an acclaimed author and journalist who has worked for The Miami Herald, The Miami News, and The Palm Beach Post.

Tags: Cancer prognosis, Cancer screening advancements, Dr. Chad Ritch, Dr. Elisa Krill-Jackson, Early cancer detection, good prognosis