What is Radiation Therapy?

Cancer incidence is rising and so is the oncologists’ armamentarium to fight this disease. As per a report by WHO, more than 50% of cancer patients require radiotherapy as part of cancer management. Radiation therapy (or radiotherapy) is a common cancer treatment that uses radiation (usually high-powered X-rays) to kill cancer cells. Radiation therapy works by damaging the DNA of cancer cells. Cancer cells whose DNA is damaged beyond the repair capacity, die; thus shrinking the tumour. 

Types of Radiation therapy:

There are two main types of radiation therapy: external beam radiation therapy (EBRT) and internal radiation therapy (Brachytherapy).

In External Beam Radiotherapy (EBRT), individual lies down on couch and treatment is delivered from outside in contrast to Brachytherapy, where applicators are inserted into or in close proximity to the tumour and then radiation delivered through radioactive sources into the applicators.

Technological advancements have been phenomenal in radiation therapy and here’s a quick understanding of how each technique is unique. Before starting with more advanced techniques, Radiation was delivered initially through apertures with fixed geometric shapes like rectangle or square like fields with uniform intensity of radiation during the entire treatment. In the present era, such fixed fields are obsolete and personalized plans are the standard.

IMRT  Intensity Modulated Radiotherapy: It involves fields of radiation that are highly conformal (exactly enveloping the target) and not giving unnecessary radiation to healthy tissues. Also, the intensity of radiation beam is tailored to meet the exact needed dose at each point. IMRT is an advanced form of precision radiotherapy.

VMAT  Volumetric Modulated Arc Therapy (VMAT) is similar to IMRT, but instead of treatment at fixed angles on the machine, treatment is delivered through the complete arc around the patient. This further improves conformality (preciseness) and decreases treatment time.

IGRT  Image guided Radiation therapy: When these high end technologies are performed, it is crucial to couple them with image guidance. Before each treatment fraction, we take a CT scan in treatment position, verify the matching of the external and internal anatomy and then deliver treatment. IGRT is unequivocal in today’s era.

SRS and SBRT/SABR  Stereotactic Radio-Surgery and Stereotactic Body Radiation Therapy/ Stereotactic Ablative Body Radiation are latest technologies where the treatment is so precisely shaped that instead of delivering the treatment over 4 to 6 weeks, radiation is delivered in less than a week using a very high dose per fraction/ treatment. They are commonly used for very early tumours or in metastatic setting (Stage IV) to ablate or manage a metastatic lesion.

Brachytherapy  It is a form of radiation therapy where radiation is delivered through radioactive sources placed inside or in close vicinity of the tumour. Prior to treatment delivery, applicators are placed in the operation theatre, commonly under anaesthesia. It is one of the most precise forms of radiotherapy.

When do we use radiotherapy?

Radiation therapy may be used independently or alongside other treatments, like surgery or chemotherapy.

• Definitive radiation therapy : When radiation is used as the main modality to treat cancer, it is called definitive radiation therapy, like in cancer cervix or head and neck cancers. In such situations, it is often combined with concurrent weekly chemotherapy.
• Adjuvant radiation therapy : When radiation is delivered after surgery to kill potential microscopic cells, it is called as adjuvant radiation therapy, for instance, breast cancer radiation therapy, after breast surgery.
• Neo - adjuvant radiation therapy : At times, we use radiation therapy prior to surgery for instance in rectal cancers to shrink the tumour and facilitate better surgery. It is called as neo - adjuvant radiation therapy.

Common cancers for which radiation therapy is used:

Definitive or adjuvant radiation in head and neck and lung cancers, adjuvant radiation is used in brain tumours, adjuvant radiation in breast cancers, gynaecological malignancies like cancers of cervix, vagina, vulva and endometrium; genito-urinary malignancies like bladder and prostate; gastrointestinal malignancies, amongst others. Radiation therapy can also be used to treat bone metastases to control pain.

We at P. D. Hinduja Hospital in Mumbai have one of the best radiation oncology department and top radiation oncologists in Mumbai, India with all the modern and state of the art infrastructure for radiation therapy in cancer care. For more queries and guidance, you may book an appointment with Dr. Ritika Harjani Hinduja, Consultant - Radiation Oncology on 022 6766 8181 / 022 4510 8181