What is Forward IMRT?

Breast cancer is one of the leading causes of mortality in women with cancer. Breast cancer can often be managed with conservative surgery if detected at an early stage. Postoperative radiotherapy has been used as a standard of care for patients with early-stage breast cancer surgery. However, certain risks of late complications may arise during a long-expected disease-free interval.

Late toxicity and complications after radiation therapy treatment for breast cancer include heart and lung issues due to their close proximity to the cancer-affected area. Advances in clinical oncology, while incorporating the power of artificial intelligence in medical sciences, have led to a drastic decrease in the possibility of the occurrence of side effects when cancer is in the remission stage post-surgery.

Before the 2000s, cancer treatment and management using radiation involved giving radiation from two to four sides, which used to be challenging due to the proximity of unaffected organs at risk (such as the heart and lungs in the case of breast cancer). This led to complications in those organs and parts of the body in the long term. Further advancements during the 2000s allowed radio-oncologists to concentrate the area of radiation even more, aiming to avoid the adjoining vital organs. Radiation in the form of 3-Dimensional Conformal Radiotherapy (3D CRT) could make this possible.

With the advent of more powerful computers and enhanced MRI and PET-CT scanning, breakthroughs in clinical oncology emerged in the form of intensity-modulated radiotherapy (IMRT). This advancement enabled radio-oncologists to focus on the target area and bend the radiations while controlling the curvature of dose delivery volume as required. This has drastically reduced the dose received by the organs at risk (OARs), providing a double benefit of minimising long-term complications and effects on the OARs. The assessment of the area affected by cancer before administering radiation therapy helps radio-oncologists manually plan the procedure and map the areas of impact for targeting radiation therapy treatment. This manually planned treatment for cancer is medically termed as “forward IMRT.

What is IMRT?

 Intensity-modulated radiotherapy (IMRT) is a relatively newer technology in the field of cancer treatment, employed as a component of adjuvant care through radiation therapy. Essentially, IMRT represents an advanced iteration of 3D CRT and holds particular value in managing complex treatment volumes, facilitating enhanced tumour control via escalated dosage, all the while minimising exposure to nearby critical organs. In IMRT, radiation is delivered through beams featuring multiple intensity levels within each individual beam. This innovation allows for the creation of concave dose distributions and stricter margins. Furthermore, thanks to the automation inherent in IMRT, radiation emission can be blocked when a critical organ lies in the path of the beam. Such a level of precision was unattainable using conventional radiotherapy methods.

Computed Tomography (CT) scanning substantially enhances the precision of defining critical organs as well as the location and extent of the tumour. A 3-D target volume is reconstructed by identifying the tumour and plotting its location for visualising the volume to be irradiated. The radiation beams are then concentrated on the targeted tumour while sparing the healthy tissues and organs that surround it. Consequently, IMRT enhances the potential to reduce long-term complications by concentrating the delivered dose to improve coverage. This approach could lead to improvements in tumour control and the survival of critical organs while also minimising the risk of late toxicity.

What is Forward IMRT?

When IMRT is manually planned for each unique case instead of using an automated computer method, it is called Forward IMRT. It is essentially a hybrid of IMRT and 3D CRT. According to international recommendations and guidelines, forward IMRT yields optimum results for the treatment of breast cancer, particularly cancer of the left breast when used in conjunction with the Deep Inspiratory Breathing Hold (DIBH) technique to limit the amount and impact of the dose reaching the patient’s heart.

What is DIBH Technique?

Deep Inspiratory Breathing Hold (DIBH) is a radiation therapy technique used for patients receiving radiotherapy in the chest region. It reduces the amount of radiation that reaches the heart by filling the lungs with air. The DIBH technique involves holding the breath for up to 20 seconds at a time, during which the radiation is administered.

The DIBH technique may be applied to patients undergoing radiation therapy for:

• Left-sided breast cancer
• Tumours in the chest or upper abdomen region
• Chest lymphoma

According to a study, radiotherapy treatment for left-sided breast cancer using the DIBH technique shows significant reductions in doses to the heart compared to the free breathing technique. While there is a slight reduction in lung dose with this technique, overall implementation of DIBH may lead to reduced irradiation to the heart and lungs without compromising target coverage.

Breast Cancer Treatment Using Forward IMRT

Post-operative or adjuvant care for breast cancer patients using conventional radiation therapy offers significant benefits in terms of local tumour control and survival. However, long-term follow-up studies have shown increased long-term side effects for patients as comorbidities, which include one or more of the following complications:

• Cardiac diseases
• Lung damage
• Rib fractures
• Breast distortion
• Pain

The use of IMRT shows an improvement in dose targeting and uniformity, thereby avoiding impacts on adjacent healthy tissues and organs at risk, resulting in an improved cosmetic outcome. The wedge filter angles for 3D CRT and two adjunctive segments of IMRT beams are optimised to achieve the best achievable homogeneous target coverage of the breast tumour. This procedure involves using two additional beams to enhance the coverage beams: two tangent beams and two at a 15-degree angle. The Forward IMRT technique can significantly improve dose distribution, particularly in patients with larger breast size, where forward tangent IMRT tends to be more beneficial in sparing the ipsilateral lung.

Advantages of Forward IMRT

 Improves coverage uniformity, particularly for concave target volumes.

1. Enables sparing of tissue and critical organs.
2. Allows for dose escalation to focus on one or more target volumes.
3. Provides controlled variation in dose distribution

Forward IMRT Treatment at Apollo Hospitals Karnataka

At the Department of Radiation Oncology at Apollo Hospitals, our critically acclaimed radio-oncologists have been engaged in continual research through clinical trials to improve the success rate and quality of medical care provided to our cancer patients. Among the various sub disciplines within Radiation Oncology, we specialise in providing exceptional medical treatment for a wide array of patient conditions using the most advanced technology.

Intensity-modulated radiotherapy is a rapidly progressing area of research and is undergoing clinical trials for the treatment of various cancers. Forward IMRT is particularly valuable for the treatment of left-sided breast cancer when used in conjunction with the DIBH technique. In collaboration with our specialised radiologists, who provide valuable contributions to map the cancer tissue for precise planning and delivery of advanced radiation techniques, we can deliver the most effective radiation therapy treatments for adjunctive and postoperative care of our patients.

We offer Forward IMRT in conjunction with the DIBH (Deep Inspiratory Breath-Hold) technique for treating left-sided breast cancer and lung cancers. Our team of radiation oncologists, radiation therapists, and medical physicists collaboratively plan and administer DIBH to ensure the highest level of safety and dose accuracy. We have a specialised team dedicated to planning and delivering DIBH. In addition, other medical professionals, including nurses and allied health practitioners, provide unwavering support and care throughout the journey toward cancer remission.