A comparison of the risks of in-breast recurrence after a diagnosis of dcis or early invasive breast cancer

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4. DISCUSSION

Some authors suggest that the term dcis is misleading because it implies a de facto cancer⁴^,⁵, and some suggest replacing “dcis” with “ductal intraepithelial neoplasia”¹². Consequently, a women or her physician might feel pressured to treat the lesion as a cancer, and treatment might be unnecessary (it is unclear whether revision of the nomenclature would lead women to experience less—or more—distress and confusion¹³).

In a recent letter to the editor, Omer et al.⁴ reported that if dcis were to be framed as a “high-risk condition” rather than a cancer, then more women than not (at least in their hypothetical sample) would opt for a nonsurgical treatment. We suspect that the responses of women faced with this choice in reality—rather than in a “what if” scenario—might differ, and yet the issue is nevertheless an important one. Others believe that the term “cancer” is appropriate, given that dcis is associated with a nontrivial risk of in-breast recurrence and mortality²^,³^,¹⁴^,¹⁵. They believe that treatment is indicated and that many women who are not treated should be¹⁴^,¹⁵.

In-breast recurrence is not uncommon after dcis; Collins et al.² estimate the risk to be roughly 20% at 10 years. Wapnir et al.³ estimate the risk of in-breast recurrence among dcis patients treated with breast-conserving surgery alone to be 19.4% at 15 years. It has been argued that, given the non-inevitability of progression, dcis falls short of cancer. Esserman et al.¹⁶ correctly identify overdiagnosis—defined as “the probability that a tumour if left unattended, would not become clinically apparent or cause death” and largely a consequence of screening—as a relevant issue.

Overdiagnosis becomes particularly important when associated with overtreatment: that is, as evidenced by the current trend in the United States to treat unilateral cancer with bilateral mastectomy¹⁷. But overdiagnosis is a feature of both dcis and invasive cancers identified through screening. Several recent studies suggest that some cases of invasive breast cancer also fail to progress¹⁸^,¹⁹. In particular, small node-negative cancers that are nonpalpable and diagnosed through mammographic screening might be examples of overdiagnosis¹⁰^,²⁰. In two studies, progesterone receptor expression was a good predictor of indolent behaviour¹⁰^,²¹. Several authors have demonstrated that palpability is a strong prognostic factor for early-stage invasive breast cancers⁶^,⁸^,¹⁶. Kerlikowske and colleagues²² found that, among women with dcis, tumour palpability was a strong risk factor for in-breast invasive recurrence. Most cases of dcis are now diagnosed through mammographic screening, and so it is apt to compare nonpalpable cases of dcis with nonpalpable cases of invasive cancers (and to control for tumour palpability when making relevant comparisons of recurrence rates between groups). We show here that, in the absence of treatment after breast-conserving surgery for mammographically-detected cancer, the rates of in-breast recurrence are approximately the same for dcis and for small invasive cancers. We attempted to control for differences in prognostic factors other than the presence of invasion, and therefore the comparison group was restricted to small node-negative invasive cancers. No case or control received chemotherapy. In this head-to-head comparison, the (adjusted) risk of progression to in-breast recurrence was roughly the same.

Weaknesses of our study include a relatively small sample size, the lack of a formal pathology review, and lack of inclusion of grade and other markers of malignant potential (such as comedonecrosis) in the model. Kerlikowske and colleagues²² reported that nuclear grade was an independent predictor of local recurrence, but Collins et al.² did not. Likewise, we had no data on the margin status of the study patients, and positive margins have been positively associated with the risk of in-breast recurrence²^,²². It is likely that biomarkers will be identified in future that will better help to predict cancer recurrence after dcis, but that possibility does not negate the validity of the present observations: When dichotomized by any predictive marker, some women will face a higher risk, and others, a lower risk of progression. Based on our data, it might be anticipated that the biomarkers that predict recurrence after dcis are the same ones that predict recurrence after small invasive cancers.

A formal pathology review might possibly have found some cases of dcis to be invasive (and vice versa), but we had access to the same information as the surgeon and the oncologists who decided whether to offer chemotherapy and radiotherapy. Collins et al.² excluded 17% of their cases after a central pathology review. All cancers in the present study were less than 2 cm in size. We did not classify tumour size in the dcis cases, but tumour size was not a predictor of in-breast recurrence in our study.

We examined local recurrence only; the other relevant outcome is breast cancer–specific mortality. It cannot be assumed that the risks of distant recurrence and death will also be the same for the two groups, and it is our intention to expand the cohort and to follow the women for mortality. We did not distinguish between invasive and noninvasive recurrences. Some of the cases of in-breast recurrence in the dcis group are expected to be noninvasive and a preponderance of the recurrences in the invasive group are expected to be invasive, but those data are not currently available.

— Update: 15-02-2023 — cohaitungchi.com found an additional article More intensive treatment of DCIS reduces the risk of invasive breast cancer from the website www.health.harvard.edu for the keyword risk of new breast cancer after dcis.

Breast cancer screening with mammography or other tools (such as MRI) has increased the rates of diagnosis of very early breast cancers knowns as DCIS (ductal carcinoma in situ). As opposed to invasive breast cancers, DCIS cancers are confined to the local area and have not spread to deeper tissues or elsewhere in the body. With increased rates of diagnosis, there has been considerable controversy about the true risks of DCIS and the best treatments, with some suggesting that women are being overtreated for a condition that does not substantially increase the long-term risk of death, and others advocating more intensive preventive treatment among women with DCIS.

Long-term outcomes for women with and without DCIS have been limited, until now

A recent study published in The BMJ offers the best data so far on the risks associated with DCIS and the impact of different treatments. In the study, more than 35,000 women diagnosed with DCIS via mammography were followed for up to 20 years to see if they developed invasive breast cancer or died of breast cancer.

Overall, the researchers found that having DCIS more than doubled the risk of developing invasive breast cancer and increased the risk of dying of breast cancer by 70%, compared with the general population. Moreover, the researchers observed that more intensive treatment of DCIS was associated with lower risk of invasive breast cancer. Compared to women who had both breast-conserving surgery (lumpectomy) and radiation therapy, those who had lumpectomy alone had 43% higher rates of breast cancer, and those who had mastectomy had 45% lower rates of breast cancer. A larger DCIS-free margin in the biopsy sample was also associated with lower rates of developing invasive breast cancer. For women with estrogen receptor-positive DCIS, hormone treatment to reduce estrogen levels was associated with lower risk of invasive breast cancer.

The findings from this new study are broadly similar to a US study of more than 100,000 women with DCIS that found an 80% higher risk of dying of breast cancer in women with DCIS than in the general population, although that study couldn’t determine how the DCIS was diagnosed. A Danish study also found that women with DCIS who were treated with mastectomy had lower rates of invasive breast cancer in that breast than those treated with more conservative surgery, with or without radiation therapy.

What does the new research mean for a woman who is diagnosed with DCIS?

This study showed that increased cancer risk persisted for more than 15 years after a diagnosis of DCIS, and that more intensive therapy than lumpectomy alone — whether with mastectomy, radiation therapy, or endocrine therapy — reduced the risk of invasive breast cancer among women with DCIS. The lowest risk of invasive breast cancer was in women who chose mastectomy.

The risk of invasive breast cancer was seen regardless of severity of DCIS. Women who had low- or moderate-grade DCIS, as well as high-grade DCIS, had long-term increased risk.

Women who are recently diagnosed with DCIS should work with their treatment team to weigh the best individual treatment strategies based on their preferences and other health conditions. This new research validates the need to consider the long-term consequences of DCIS when making treatment decisions, and it may prompt doctors and patients to consider more intensive treatments to reduce later risk of invasive breast cancer and risk of dying of breast cancer. While no details on surveillance strategies, such as regular mammograms or other exams, were presented in this study, based on these results, patients with DCIS should continue active surveillance for breast cancer for decades after their diagnosis.