Treatment / Radiation therapy

Radiation therapy

A treatment option that attacks the cancer with penetrating beams of energy waves or streams of particles that can destroy cancer cells.

Purpose of radiation therapy

Radiation therapy Radiation therapy The use of radiation to kill cancer cells and shrink tumors. Merkel cell carcinoma is a highly radiation sensitive cancer in most cases. , also referred to as radiotherapy or XRT, is the treatment of cancer cancer A term used to describe diseases in which abnormal cells continually divide without normal regulation. Cancerous cells may invade surrounding tissues and may spread to other regions of the body via blood and the lymphatic system. with penetrating beams of energy waves or streams of particles that can destroy cancer cells. Radiation therapy is delivered to the cancer cells and a margin margin The edge or perimeter of the tissue removed in cancer surgery. The margin is described as "clear" or "negative" when the pathologist sees no sign of cancer cells under the microscope, suggesting that all of the cancer has been removed. The margin is described as "positive" or "involved" when the pathologist finds cancer cells in the edge of the tissue. This suggests that not all of the cancer has been removed. Certain cancers such as Merkel cell carcinoma can have negative microscopic margins despite residual cancer cells being left behind because MCC often "skips" via local lymphatics to adjacent areas and does not grow a single continuous mass. of surrounding apparently normal tissue, referred to as the radiation field. Radiation therapy damages the genetic material of cancer cells making them unable to grow. Radiation therapy also damages healthy cells in the field of radiation. Adjuvant radiation therapy is radiotherapy that is used to destroy any cancer cells that may remain after surgery has removed all of the tumor that is visible.

Our analysis of the available literature and our experience caring for MCC patients since 1999 show that radiotherapy is associated with a statistically significant improvement in local local Affecting only the site of origin, without evidence of spreading. Compare to systemic. and nodal recurrence. Some studies also suggest that adding radiation may improve a patient’s chance of survival, but this is more controversial.1 Where wide excision excision The removal of tissue of interest by surgery. is not possible, a recent study suggests that radiotherapy alone may be nearly as effective as both radiotherapy and surgery. These data suggest a role for radiotherapy for many patients with stage stage Physicians determine the stage of cancer by performing physical exams and tests. Stages describe the extent of cancer within the body, especially whether the disease has spread (metastasized) from the primary site to other parts of the body. I, II & III disease.

Local recurrence is 3.7 times more likely if surgery only
Local recurrence is 3.7 times more likely if surgery only

A Closer Look

 The dose of radiotherapy is measured in units called Gray (Gy). The total dose of radiation therapy should be greater than or equal to 50 Gy. Radiation therapy is usually administered in a doctor’s office in divided doses for 10-15 minutes, 5 days a week (e.g., Monday through Friday) over a set number of weeks (most commonly for 5 weeks).

Who this works for

Radiation therapy can markedly lower the risk of MCC recurrence in the irradiated areas ( primary site primary site The area of the body where the abnormal tissue first appeared. and or draining lymph node draining lymph node The particular lymph node(s) to which the lymph fluid from an area of tissue flows. basin). We typically recommend patients receive radiation if they have a significant risk of local-nodal recurrence (typically >15%), are generally healthy, want to maximize the chance of not having the cancer come back in the areas at risk, and can travel daily to a local radiation therapy facility for the 5-6 week treatment period.

Who this doesn’t work for

Patients who have very low risk disease, as defined by having all of the favorable features below, are likely to benefit very little from adjuvant radiation therapy.

We are currently not routinely recommending radiation therapy for such low-risk cases. Features include:

  1. Primary tumor ≤2 cm in largest dimension
  2. Negative sentinel lymph node biopsy sentinel lymph node biopsy Removal and examination of the "sentinel" lymph node(s). Sentinel nodes are the first lymph nodes to which cancer cells spread from a primary lesion. To identify the sentinel lymph node(s), a radioactive substance and/or dye is injected near the primary lesion. The surgeon uses a Geiger counter to find the lymph node(s) containing the radioactive substance or looks for the lymph node(s) stained by the dye. The surgeon then removes the sentinel lymph node(s) and sends them to a pathologist to check for the presence of cancer.
  3. No chronic immune suppression (HIV disease, leukemia/lymphoma, transplant of heart or kidney or liver)
  4. No lympho-vascular invasion in the primary tumor ( pathologist pathologist A doctor who specializes in identifying diseases by examining cells and tissues under a microscope. may need to be asked to go back to the original biopsy biopsy The removal of cells or tissue in order to determine the presence, characteristics, or extent of a disease by a pathologist usually using microscopic analysis. and specifically comment on this feature’s presence or absence).
  5. Confidently negative microscopic margins after excision

Side effects

Common side-effects of radiation therapy in the area being treated include loss of hair, skin irritation (like a sunburn), and changes in the color and texture of the skin. Radiation to a draining lymph node lymph node A rounded mass of lymphatic tissue that is usually surrounded by connective tissue and about the size of a green pea. Lymph nodes filter lymphatic fluid, also know as lymph, which is fluid that drains from the tissues of the body and contains immune cells. Cancer cells often travel through lymph vessels and lodge and grow in lymph nodes, sometimes causing the nodes to markedly increase in size. basin may cause swelling of the arm or leg on the same side that may be long-lasting, and is more likely if extensive nodal surgery has also been carried out. A frequent side effect is fatigue, which usually resolves within a month or two after the radiotherapy is stopped. Accordingly, it is important to eat a well-balanced diet and get plenty of rest. A radiation oncologist radiation oncologist A doctor who specializes in using radiation to treat cancer. X-rays ("photons") are used to penetrate more deeply and "electron" beam therapy is used to target more superficial cancer sites. may adjust the dose or schedule of radiation therapy based on the side effects. Localized radiation therapy typically does not lead to nausea, vomiting, or hair loss outside of the irradiated area.

Often used in conjunction with

Surgery and/or systemic systemic Affecting the entire body. Compare to local. therapy


Do I need radiation?

Radiation is one type of treatment used in some cancers. Radiation Oncologists plan and administer this type of treatment. Radiation therapy is often an important part of treatment for MCC. Usually radiation is given to the primary site (on the skin) of the tumor. If the sentinel lymph node biopsy was positive, radiation is often indicated to those lymph nodes.

What is the best way to decide if an MCC patient should have radiation?

While there is agreement that radiation therapy lowers the risk of MCC recurrence, there is great controversy as to exactly which patients should receive this therapy.  The side effects, cost, and inconvenience of radiation therapy can be significant. Patients with extremely low risk disease should not receive radiation, and patients with high risk disease should be offered this therapy. Determining which moderate-risk disease patients should receive radiation is very tricky and needs to be customized for each patient’s philosophy regarding recurrence risk versus side effects.  Ideally, this discussion should take place with a multi-disciplinary team that is very familiar with the relevant literature and the risks and benefits of radiation therapy for MCC.

What is single-fraction radiation for MCC?

In some cases, especially if MCC has spread beyond the local-nodal area, we have successfully used a single, larger dose (8 Gy) of radiation to shrink and sometimes eliminate a given metastatic lesion. This approach has relatively few side effects and may work nicely together with systemic immune stimulation therapy.  We described this approach in a 2015 report on 93 tumors treated in 26 patients.

Should all patients participate in complementary or alternative therapies for their cancer?

No. Participation in these ‘scientifically unproven’ approaches to cancer therapy should be strictly voluntary.  Some patients are very keen to use these approaches and others have no interest. We never push our patients to engage in any specific alternative approach.

Understand the Science

The following clinical publications and scientific research provide additional in-depth information about radiation therapy.

Postoperative radiation therapy is associated with a reduced risk of local recurrence among low risk Merkel cell carcinomas of the head and neck

Purpose: Merkel cell carcinoma (MCC) is a rare and often aggressive skin cancer. Typically, surgery is the primary treatment. Postoperative radiation therapy (PORT) is often recommended to improve local control. It is unclear whether PORT is indicated in patients with favorable Stage IA head and nec...

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Adjuvant Radiation Therapy and Chemotherapy in Merkel Cell Carcinoma: Survival Analyses of 6908 Cases From the National Cancer Data Base.

Merkel cell carcinoma (MCC) has a high risk of recurrence after initial surgical therapy. Adjuvant radiation therapy (RT) and chemotherapy may be used to reduce the risk of locoregional and systemic recurrence, respectively, but there are conflicting data regarding their impact on survival. We perfo...

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Adjuvant radiation therapy is associated with improved survival in Merkel cell carcinoma of the skin.

Merkel cell carcinoma (MCC) is a rare cutaneous malignancy. Because of the absence of randomized studies, the real benefit of adjuvant radiation therapy in MCC is unclear. The aim of this study was to better define the role of adjuvant radiation therapy in the management of MCC.

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Adjuvant local irradiation for Merkel cell carcinoma.

The June 2006 issue of the Archives of Dermatology features several articles on Merkel cell carcinoma discussing the role of sentinal lymph node biopsy in prognosis and improved therapy, the importance of adjuvant radiation and an editorial highlighting the management and treatment of MCC. This stud...

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Recurrence after complete resection and selective use of adjuvant therapy for stage I through III Merkel cell carcinoma.

Merkel cell carcinoma (MCC) is a rare cutaneous neuroendocrine neoplasm whose natural history is poorly understood. Here, the authors describe their experience with a large cohort of patients who were treated at a single institution to describe patterns of recurrence after curative therapy.

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Single-fraction radiation therapy in patients with metastatic Merkel cell carcinoma.

Merkel cell carcinoma (MCC) is an aggressive, polyomavirus-associated cancer with limited therapeutic options for metastatic disease. Cytotoxic chemotherapy is associated with high response rates, but responses are seldom durable and toxicity is considerable. Here, we report our experience with pall...

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