Treatment for Micrometastases in Lymph Nodes

 Finding out that one has breast cancer is the kind of news no one wants to hear from their doctor, but for most women breast cancer is not a terminal diagnosis.1 Breast cancer is treatable. Breast cancer exists in different forms and stages which determine how aggressive treatment should be, what optimal treatment options are and how likely the cancer is to metastasize or spread.

This article addresses the topic of micrometastases. It will answer questions such as: What are micrometastases? What is the relationship between breast cancer and micrometastases? How is a surgeon likely to respond if micrometastases are found in the lymph nodes?

Micrometastases and Breast Cancer

 Micrometastases are small groups of cancer cells found outside the primary tumor. Micrometastases are sometimes located in lymph nodes near the tumor, and studies have shown that the presence of micrometastases is a good indicator of whether or not the cancer is spreading to other parts of the body.2

Previously, when lymph node excision was necessary, surgeons would routinely remove large sets of lymph nodes to prevent any remaining cancer from spreading through the body. These surgeries required long recovery times and would leave large scars. But newly published information has gradually changed how oncologists and surgeons practice. There is strong data to support less extensive and invasive methods of lymph node evaluation that are safe and effective.

One review entitled, “Breast Cancer and Sentinel Lymph Node Micrometastases: Indications for Lymphadenectomy and Literature Review,” published in the Journal of Surgery, examined different studies on the presence of micrometastases. The review concludes that women whose lymph nodes are negative for micrometastases need fewer nodes removed than women who had confirmed micrometastases in their nodes.3 The body of research on micrometastases has changed breast cancer treatment. Now, surgeons will perform a sentinel lymph node biopsy to determine the extent of nodal surgery a woman needs before large numbers of lymph nodes are removed.

What Is a Sentinel Lymph Node Biopsy?

 During a sentinel lymph node biopsy, the surgeon removes the sentinel lymph node to look for micrometastases.4 The “sentinel” lymph node is the node or nodes that are the “first” draining lymph nodes from the tumor and are most likely to be the next target of cancer cells before they move any further throughout the body. It is possible to have one or more sentinel lymph nodes removed during the “biopsy” as they are grouped together in small clusters and more than one node may be involved.

A sentinel lymph node biopsy is the first step before surgeons take further measures and remove additional lymph nodes. If a sentinel lymph node biopsy is negative for micrometastases, removal of additional nodes is usually not necessary. If the sentinel node biopsy results are positive for micrometastases, surgeons will use more invasive techniques to remove additional lymph nodes after the initial node evaluation.

Sentinel lymph node biopsies help surgeons and patients avoid unnecessary surgery. These biopsies require less recovery time and leave smaller scars than removal of multiple lymph nodes. A sentinel lymph node biopsy still has associated risks including swelling, fluid buildup at the biopsy site, numbness, tingling, discomfort and difficulty moving the affected body parts.4

Axillary Lymph Node Dissection

 An axillary lymph node dissection is a more invasive surgery than a sentinel lymph node biopsy. In an axillary lymph node dissection, additional lymph nodes are removed in order to evaluate the extent of nodal involvement and to prevent the cancer from spreading further. There are three different levels of axillary lymph nodes. Level I lymph nodes are found at the lower edge of the pectoralis minor muscles. Level II lymph nodes are located underneath the pectoralis minor muscles and level III lymph nodes are found above the pectoralis minor. An axillary lymph node dissection typically removes the first two levels of lymph nodes, sparing the nodes above the muscle.5

 Based on the number of lymph nodes that show signs of cancer, a surgeon will usually remove somewhere between five and 30 nodes. In determining whether to remove a given node, the surgeon looks for any evidence of cancer in the node rather than how much cancer is present.5 An axillary lymph node dissection usually happens at the same time as mastectomy or breast-conserving surgery, but can also be postponed if need be.6

 Historically, axillary lymph node dissection was the first method surgeons used to treat all breast cancer patients who needed lymph nodes removed. Since the body of knowledge surrounding the benefit of sentinel lymph node evaluation prior to axillary node dissection has been established, full node dissection is now used only in more extreme circumstances.6 Some of the situations in which a surgeon will recommend sentinel lymph node biopsy include breast cancer when there are multiple tumors, Ductal Carcinoma in Situ when mastectomy is planned, women with previous breast cancer or axillary node surgery, and women who have been treated with chemotherapy before .2

There is an ongoing debate about the effectiveness of axillary lymph node dissections. Some studies suggest that axillary lymph node dissections do not significantly improve a woman’s chances of survival, especially when only a small number of cancer cells are present in the sentinel lymph nodes.7 The Journal of the American Medical Association (JAMA) published research on this issue. In a randomized clinical trial, they found that women who received axillary lymph node dissection experienced more associated side effects as a result of the surgery, but did not see significant improvement in disease-free survival.8

 Studies like this need to be treated with healthy skepticism until further research is done. The authors recognized that there were certain flaws with the study, making it less than reliable for the time being. These flaws included low recurrence rates and a small sample size. However, it is important to remember that new research is being done to improve treatment options for women with micrometastases in their lymph nodes, and there are discoveries yet to be made.

Conclusion

Micrometastasis is just one of many topics you will learn about if you or someone you know has been diagnosed with breast cancer. Just know that at some point your doctor will look for micrometastases to get a better understanding of the extent of disease and how treatment should proceed. Depending on the status of micrometastases found in the sentinel lymph nodes, an oncologist may recommend a variety of different treatment options, such as further lymph node removal, radiation therapy, chemotherapy after surgery and treatment with hormonal therapy.2

Research continues and treatment options for those with micrometastases continue to improve over time. Given the current state of research, technology, diagnostic techniques and surgical technology, oncologists are well-prepared to address and manage micrometastases in breast cancer.

References

  1. Breast Cancer Survival Rates. American Cancer Society. Aug. 18. 2016. https://www.cancer.org/cancer/breast-cancer/understanding-a-breast-cancer-diagnosis/breast-cancer-survival-rates.html
  2. Micrometastases in Lymph Nodes Need Treatment. BreastCancer.org. June 4, 2009. http://www.breastcancer.org/research-news/20090604
  3. Zanghi G, Di Stefano G, Caporetto D, et al. Breast cancer and sentinel lymph node micrometastases: indications for lymphadenectomy and literature review. Journal of Surgery 2014;35(11-12):260-265 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4321503/
  4. Sentinel Lymph Node Biopsy. National Cancer Institute. National Institutes of Health. Aug. 11, 2011. https://www.cancer.gov/about-cancer/diagnosis-staging/staging/sentinel-node-biopsy-fact-sheet
  5. Axillary Lymph Node Dissection. BreastCancer.org. Jan. 22, 2015. http://www.breastcancer.org/treatment/surgery/lymph_node_removal/axillary_dissection
  6. Lymph Node Surgery for Breast Cancer. The American Cancer Society. June 1, 2016. https://www.cancer.org/cancer/breast-cancer/treatment/surgery-for-breast-cancer/lymph-node-surgery-for-breast-cancer.html
  7. Extensive Lymph Node Removal Doesn’t Improve Survival in Some Women with Early-Stage Breast Cancer. National Cancer Institute. National Institutes of Health. October 10, 2017. https://www.cancer.gov/types/breast/research/micromets-sentinel-nodes
  8. Giuliano A, Ballman K, McCall L, et al. Effect of Axillary Dissection vs No Axillary Dissection on 10-year Overall Survival Among Women with Invasive Breast Cancer and Sentinel Node Metastasis: The ACOSOG Z0011 (Alliance) Randomized Clinical Trial. JAMA 2017;318(10):918-926.
    https://www.ncbi.nlm.nih.gov/pubmed/28898379

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