Hodgkin’s Lymphoma: An Environmental Scan
Table of Contents
3.10 Gold-Standard Treatments: Radiation and Chemotherapy
The information contained within this report regarding treatment is simplified in order to provide an overview of treatment and the basic components involved; however, clinically the various types of chemotherapy agents, exact courses and duration of treatments along with the numerous patients and clinical factors affecting a patient’s treatment regime are quite complex. (For additional information including a much deeper presentation of the details surrounding treatment for HL see list of citations at the end of this report).
HL is a treatable cancer for the vast majority of individuals, especially when the diagnosis is made during the early stages and when patients are younger in age. A significant consideration in the treatment of HL is ‘late effects’ or the consequences for individuals later in life as a result of their initial treatment. The goal is to cure HL completely while at the same time reduce the number of adverse health effects later on as a result of under-going initial treatments (see Late Effects, section 3.11). The specific treatment modality and regime an individual with HL will undergo is a decision based on a number of factors including: the sub-type of HL, the stage of the disease, the rate at which the disease is assessed at progressing, the age of the patient and their overall health status.
Historically, radiation therapy (RT) was used alone to treat early stages of HL; however, as researched evolved, it became evident that wide exposure to radiation contributed significantly to poor health outcomes later in life (Raemaekers and van der Maazen 2008). Involved-field radiation therapy (IFRT) is when radiation treatment is confined to a particular place on the body versus extended field radiation that covers a much larger area. The goal is to confine the radiation treatment to the smallest area possible while ensuring the field includes the cancer cells. As previously discussed, HL tends to progress in a uniform fashion from one lymph node to the next thus, it is possible to predict the pattern and match the radiation respectively. Cancer cells reproduce faster than normal cells in the body and radiation therapy targets these rapidly dividing cells. The radiation damages the DNA or genetic material in the cell that controls cell growth. This allows cancer cells, which are not as adept at repairing themselves to be destroyed.
The amount of radiation used in IFRT, as with all other radiation therapies, is measured in gray (Gy), and varies depending on the type and stage of cancer being treated. Radiation treatments are divided into several small sessions, called fractions. Most treatments with involved field radiation are completed in 4 to 5 weeks. The duration of treatment depends on the dose delivered. IFRT is commonly given after primary chemotherapy treatments; the dose is often based on clinical assessment of how much disease remains. The side effects of radiation depend on the treatment and dose and the part of the body that is treated. During radiation therapy, patients frequently experience extreme fatigue, particularly during that last weeks of treatment. Radiation increases the risk of late effects. Receiving IFRT increases the risk of developing cancer in the organs which were within the radiation field (such as lung, breast, or stomach cancer) 10 or more years after initial treatment (A. Engert et al. 2009).
With the advent of several chemotherapy drugs, a combination of chemotherapy drugs and radiation therapy used together are standard practice. However, randomized controlled trials have failed to demonstrate that the use of combination chemotherapy and radiation is more effective than chemotherapy alone, thus it appears that some individuals, particularly in the very early stages with favorable prognostic factors may in fact be over-treated (Seam et al. 2009).
There are two main reasons for using a combination of chemotherapy drugs, which allow the physician to administer a lower dose of any one particular drug with the goal of reducing the impact of side effects. Side effects from chemotherapy include temporary or permanent infertility, an increased risk of infection, and potential damage to other organs, including the heart or lungs, as well as reversible hair loss. Additionally, using more than one type of chemotherapy drug also reduces the likelihood that an individual under-going chemotherapy will develop a resistance to the drug itself. The most common combination of chemotherapy drugs used for HL is known as ABVD; however there exists variation in the approach to treatment regimes, including specific drug combinations depending on a variety of patient characteristics and clinical factors (Diehl and Fuchs 2007).
According to the European Society of Medical Oncology (ESMO) clinical practice guidelines, classical HL (cHL), when diagnosed at the earliest of stages, a brief course of combination chemotherapy followed by involved-field radiation therapy is recommended (2 cycles of ABVD followed by 30 Gy of IFR). There is on-going discussion of whether or not radiation can be omitted for this group of patients while still realizing the high cure rates. For patients whose disease has progressed beyond early stages but not yet classified as advanced, they are placed into the intermediate group and have the same chemotherapy treatment as early stages albeit 2 additional rounds of chemotherapy. For patients with the most advanced disease, chemotherapy treatment with either ABVD or other combination chemotherapy drugs using up to 8 cycles is recommended followed by 30 Gy of radiation. Similarly, treatment for the sub-type non-lymphocyte predominant Hodgkin’s lymphoma, the ESMO guidelines are the same as for cHL with the exception of the early stage, which is treated with radiation alone (A. Engert et al. 2009).