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Ductal carcinoma in situ (DCIS), also known as stage 0 breast cancer, is categorized as a non-invasive or pre-invasive form of cancer. Despite its non-invasive nature, treatment is necessary to prevent its progression into invasive breast cancer. Understanding the prognosis, treatment options, and ongoing research is crucial for managing stage 0 breast cancer effectively.
"It's essential to recognize that DCIS still carries risks and requires careful consideration," emphasized Marleen Meyers, MD, a medical oncologist and the director of the Perlmutter Cancer Center Survivorship Program at NYU Langone Health, in an interview with Health.
DCIS, or ductal carcinoma in situ:
affects the cells within the milk ducts of the breast. These ducts serve as channels for transporting milk to nursing infants. When cells within one of these ducts undergo mutations and begin to multiply in a manner resembling cancer cells, DCIS develops. It is estimated that approximately one in five newly diagnosed cases of breast cancer is DCIS. Since these abnormal cells typically remain confined within the duct and do not spread to surrounding tissues, DCIS is often referred to as stage 0 breast cancer
The diagnosis of DCIS:
has seen a significant surge in the past two decades, as noted by Julia White, MD, director of breast radiation oncology at the Ohio State University Comprehensive Cancer Center. In the 1990s, only approximately 15,000 to 18,000 cases of DCIS were identified annually. However, this number has more than tripled, surpassing 51,000 cases per year.
Dr. White attributes this increase to the widespread adoption of mammography screening and advancements in technology, enabling the detection of very small lesions. Consequently, individuals are receiving treatment at earlier stages, reducing the likelihood of DCIS progressing beyond the milk duct and becoming invasive. Despite these advancements, the ability to predict which lesions will become invasive remains a challenge.
The outlook for individuals diagnosed with DCIS is highly favorable due to its noninvasive nature. According to a 2019 study, the survival rate after 10 years of follow-up stands at approximately 98%.
Moreover, individuals whose DCIS is managed through strategies like surgical excision, radiotherapy, or endocrine therapy also have an "extremely good" prognosis.
Is the Risk of Another Cancer Higher After DCIS?
Following a diagnosis of DCIS, individuals still face elevated risks. "When you have DCIS, it means your risk of developing another DCIS or an invasive breast cancer is higher than the general population," explained Dr. Meyers.
A study comparing women diagnosed with DCIS to those in the general population revealed that individuals with DCIS had a heightened long-term risk of developing invasive breast cancer, as well as a higher risk of death due to breast cancer within 20 years of DCIS detection during breast cancer screening.
"Whatever caused the cells to mutate will generally occur in more than one duct—and sometimes, those mutated cells can break through a duct and become invasive breast cancer," Dr. Meyers noted.
However, the exact reasons for this phenomenon remain unclear. "We don't know why some cases of DCIS have the ability to do this while others don't, so right now we want to treat all of them with at least surgery, and maybe more," she added.
Does Tumor Size Impact the Risk of Invasive Cancer Returning After DCIS?
After a person receives a DCIS diagnosis and undergoes surgery to remove the abnormal growth, the next step is to evaluate the risk of recurrence with a more invasive cancer. Tumor size plays a crucial role in this assessment, according to Dr. White. Larger DCIS areas, typically around 2 to 2.5 cm (or 20 to 25 mm) or greater, are considered significant. For lesions of this size, the general recommendation extends beyond surgery to include additional treatments like radiation and hormone therapy. Conversely, DCIS areas smaller than 2.5 cm are regarded as low-risk features of the condition.
Does the "Nuclear Grade" of DCIS Impact Treatment Decisions?
The "nuclear grade" of DCIS is also a crucial factor to consider. This grade is determined by closely examining the nuclei of cells obtained during a biopsy. DCIS is categorized into three grades:
- Low (grade 1): Resembling normal, healthy cells the most.
- Intermediate (grade 2).
- High (grade 3): Exhibiting the most abnormal appearance and fastest growth.
High-grade DCIS may be referred to as "comedo" or "comedonecrosis," indicating the accumulation of dead cells within the rapidly growing tumor. A higher grade corresponds to an increased likelihood of concurrent invasive breast cancer, either alongside the DCIS or in the future.
Can DCIS be removed with surgery?
DCIS is often treated with surgery, typically through a lumpectomy procedure. During a lumpectomy, surgeons aim to remove all cancerous cells along with a 2mm margin of healthy tissue surrounding the tumor to minimize the risk of recurrence. In cases where DCIS has spread across multiple ducts or if the tumor is large, a mastectomy, which involves removing the entire breast, may be recommended. However, some patients may choose to forgo surgery and opt for a watch-and-wait approach, especially if the DCIS is low-risk and unlikely to progress.
What are Hormone-Blocking Medicines Used For?
Hormone-blocking medications like tamoxifen or aromatase inhibitors can be prescribed to some individuals with DCIS to lower the risk of recurrence or the development of invasive cancer in the future. However, these drugs come with potential side effects, and they may not benefit everyone.
Determining the effectiveness of these medications involves testing the DCIS tumor to assess estrogen and progesterone receptor status. According to Dr. Meyers, most women with DCIS have positive hormone receptors, making them potential candidates for hormone-blocking therapy. However, for those without positive hormone receptors, these drugs may not offer significant benefits.
While these medications have been shown to reduce the risk of another cancer, they do not necessarily improve overall survival rates for DCIS patients. Dr. Meyers emphasizes the importance of considering individual risk factors when deciding whether to pursue additional treatment and reassures patients that discontinuing these medications is an option if they experience intolerable side effects.
How might a vaccine prove beneficial?
Clinical trials are ongoing, with researchers optimistic about the potential for a vaccine to activate the immune system, preventing early DCIS from advancing beyond the milk duct. Successful trials could lead to it being considered as an alternative to surgery and radiation for certain patients.
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