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Better to sacrifice brevity in favor of clarity when promoting breast cancer screening strategies

Allina study shows patients with very small breast tumors may forgo lymph node biopsies

Our Review Summary

The news release highlights a study — that joins about a dozen similar such studies over the past decade — trying to determine if looking for cancer spread in axillary (armpit) lymph nodes is worthwhile in a specific subtype of breast cancer called “microinvasive,” or “Tmic” (which refers to a tumor 1 millimeter or smaller).

It remains a controversial surgical dilemma, in part, because some studies have found evidence of microinvasive cancer spreading to the lymph nodes 12.5% of the time, while this study, in particular, found the lowest incidence — just 1.5%. The authors conclude that, based on their findings, they believe microinvasive cancer is akin to ductal carcinoma in situ (DCIS) in that spread to the lymph nodes is rare.

The researchers conclude from the study that routine node sampling in microinvasive cancer is of questionable benefit.

The news release is very succinct in describing the findings of this small (under 300 patients) single-center study. Readers need more information before they can fairly weigh the researchers’ recommendation. For example, the release only notes that spread to the lymph nodes was found in patients with “relatively large” examples of DCIS, without clarifying what “fairly large” means; doesn’t note the average followup period for study participants, or what the outcomes were at the end of the study such as breast cancer recurrence, distant metastatic disease, or death from breast cancer. The release also does not mention if other tumor factors, such as hormone receptor status, were associated with spread to the lymph nodes.

 

Why This Matters

Recent advances in mammography and an increase in screening mean more breast abnormalities are detected; however, whether they should be labeled or treated as cancer is not always clear. Removal of some of the underarm lymph nodes (sentinel node biopsy) is generally performed at the time of surgery for early stage breast cancer in order to confirm whether or not there has been spread, and to inform treatment decisions. It is often not performed at the time of breast conserving lumpectomy in cases of DCIS; however, the decision whether to not to perform sentinel node biopsy in cases of microinvasive breast cancer is controversial.

Breast cancer is staged according to tumor size (denoted as “T”) and lymph node spread (denoted as “N”). The “T” category ranges from 0-4 based on the size of the tumor in the breast. Tis represents ductal carcinoma in-situ, and T1 tumors are invasive breast cancers smaller than 2cm. Tmic is the designation used for microinvasive cancers — where the invasive component is less than 1mm.

Future research in this area will help clarify whether Tmic should be approached more like DCIS or like an invasive cancer. Less treatment would have huge implications for surgeons, health care costs, and especially the quality of life for many patients.

Criteria

Does the news release adequately discuss the costs of the intervention?

Not Satisfactory

The cost of sentinel lymph node biopsy is not included in the release. Depending on the type of biopsy performed, costs can range from a few hundred dollars to several thousand.

Does the news release adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

The lead author states: “These findings allow surgeons to select which patients with microinvasive  tumors may actually benefit from lymph node sampling, while sparing other patients from this procedure.” But the release was too vague to give readers a clear understanding of the benefits. It does not define “relatively large” in relation to the DCIS cases that were observed in the study and it and does not mention if the researchers found other factors associated with lymph node involvement.

Most importantly, health outcomes such as recurrence, the presence of metastases or death from breast cancer at the conclusion of the study were not mentioned in the release. It would also have been useful to state how long patient volunteers were followed as part of the study. According to the published research, patients were followed a mean of 4.6 years.

Does the news release adequately explain/quantify the harms of the intervention?

Not Satisfactory

The results of this study support forgoing routine axillary (armpit) sentinel lymph node biopsy to evaluate for cancer spread in cases where the invasive breast cancer is less than 1mm in size.

A potential harm of this approach is missing metastatic cancer. This is not mentioned in the release.

Apropos of this, how long the patients were followed (the mean follow-up was 4.6 years, according to the published study) is a key piece of information and was also not included in the release.

Does the news release seem to grasp the quality of the evidence?

Not Satisfactory

The release would have been much stronger had it lifted more study details from the published report and added them to the release. Readers aren’t told how patients fared during follow-up assessments and how long after initial screening these assessments occurred. Nor are we provided with any health outcomes (recurrence, presence of metastases, death) at the study conclusion. (According to the published study, no cases of recurrence, metastases or death occurred among any patients at 4.6 years. This is key information that should have been included in the release, along with some study limitations that were mentioned.) All the release tells us is  that among study volunteers with microinvasive breast cancer, just 1.5% had positive lymph nodes.

Does the news release commit disease-mongering?

Satisfactory

No disease mongering. The management of microinvasive breast cancer — which includes assessing how it spreads — remains a common surgical dilemma.

Does the news release identify funding sources & disclose conflicts of interest?

Satisfactory

The funding sources are listed in the release. No conflicts of interest are mentioned in the published study.

Does the news release compare the new approach with existing alternatives?

Not Applicable

There are no radiologic or other non-surgical diagnostic alternatives for evaluating the spread of microinvasive breast cancer to the axillary lymph nodes, so we rate this Not Applicable.

Does the news release establish the availability of the treatment/test/product/procedure?

Satisfactory

The news release does not address availability specifically but readers can glean from the release that lymph node biopsy is a common surgical procedure. The release summarizes the study’s research question: Should lymph node biopsies in tumors that are 1mm or less in size remain common practice?

Does the news release establish the true novelty of the approach?

Not Applicable

The release makes it clear that the treatment of Tmic remains controversial. It may have been worthwhile to include that the authors claim this study is the “3rd largest published series” on this topic. But that’s not a major point; hence the N/A rating.

If there is anything “novel” about this study it’s that the primary result of finding just 1.5% positive lymph nodes is the lowest rate recorded of about a dozen similar studies.  That may have been something worth bringing up in the news release.

Total Score: 4 of 8 Satisfactory

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