Question 1

What are the complications of stereotactic radiotherapy (SRT/SRS), and what is the prognosis?

Dr. Garima Singh · Accepted Answer

It depends heavily on where the tumour sits. In fractionated radiosurgery for brain tumours, the incidence of radiation necrosis runs below 10 percent, and brain edema is another recognised complication. Risk rises when the target is near a critical structure such as the motor cortex or brainstem; robust dosing data for the motor cortex are limited, but the working figure for a single SRS session is around 15 Gy to that structure. With fractionated SRT or SRS, clinicians have to be especially vigilant about the proximity of organs at risk during planning. Done with that vigilance, SRS can be delivered safely to metastatic brain lesions with minimal complications, though it demands real expertise and careful dose painting.

Question 2

What has been your experience treating pediatric cancer patients?

Dr. Garima Singh · Accepted Answer

I have treated around ten pediatric patients from Ethiopia specifically, as part of a broader pediatric caseload. Pediatric malignancy needs to be treated very carefully. In medulloblastoma, for example, craniospinal irradiation planning has to be extremely precise to prevent radiation-related toxicity. Because survival in cancers like ependymoma and medulloblastoma is often good, the most important concern becomes preventing secondary malignancy later in life, which means paying close attention to low-dose spillage, or integral dose, across the whole treatment field. For pediatric cases needing long treatment fields, we generally use tomotherapy, and we get very good outcomes.

Question 3

When is radiotherapy a viable treatment option for a patient, and when is it not?

Dr. Garima Singh · Accepted Answer

It depends on the site and the stage. In early-stage head and neck cancer, surgery alone can be sufficient, but high-risk features on post-surgical pathology can still require adjuvant radiotherapy. In locally advanced disease, radiotherapy is generally needed as part of definitive treatment. In stage IV disease, radiotherapy is mostly palliative: relieving pain, bleeding, cord compression or hemoptysis. More than 50 to 60 percent of patients need radiotherapy at some point, whether as radical treatment, adjuvant therapy or palliation, and we rely on a multidisciplinary tumour board to decide the exact timing for each patient.

Question 4

What is the guiding principle for when to integrate chemotherapy with radiotherapy, versus using either alone?

Dr. Garima Singh · Accepted Answer

We follow international guidelines. Using cervical cancer as an example: stage IA, IB and IIA disease is treated with surgery first. Adjuvant treatment then depends on the Sedlis and Peters criteria: positive margins or positive nodes call for concurrent chemoradiation; deep stromal invasion beyond one-third, a tumour over 4 centimetres, or lymphovascular space invasion, without positive margins or nodes, call for radiation alone; if none of those features are present, no adjuvant treatment is needed and the patient goes to follow-up. Locally advanced disease, stage IB3 to IVA, needs concurrent chemoradiation. Stage IVB generally starts with chemotherapy, though a bulky tumour or high nodal burden may call for six weeks of neoadjuvant chemotherapy before concurrent chemoradiation. Every site, endometrium, lung, breast, has its own guideline, and we make these calls through tumour board discussion.

Question 5

Does imaging or histopathological cell type weigh more heavily in this decision?

Dr. Garima Singh · Accepted Answer

They are complementary, not competing. Staging starts with clinical examination: if the tumour looks confined to the cervix, with no fornix or parametrial involvement and a size under 4 centimetres, surgery looks feasible on clinical grounds. MRI is then used specifically to confirm there is no parametrial invasion, which gives us a clinico-radiological diagnosis. Only after surgery does histopathology decide whether adjuvant treatment is needed. This stepwise approach, clinical exam, then imaging, then surgery, then histopathology, is important because operating on an advanced or bulky tumour without confirming operability first raises the risk of a positive margin, which then commits the patient to more aggressive treatment than necessary.

Question 6

Is there a role for radioactive bead implants (brachytherapy) in this therapy?

Dr. Garima Singh · Accepted Answer

Yes, that is brachytherapy. Historically, cervical cancer brachytherapy used preloaded sources, meaning the source had to be implanted directly. Technology has evolved to after-loading systems: the applicator, such as the Fletcher-Suit system, is placed first, and the radioactive source is then transferred into the tandem remotely through the treatment machine. That shift from preloading to after-loading has improved safety for patients and staff.

Question 7

What are the current dose constraints for organs at risk in head and neck cancer?

Dr. Garima Singh · Accepted Answer

It depends on the treatment area. For oral cavity cancers such as carcinoma of the tongue, the parotid and submandibular glands, buccal mucosa and dysphagia-related structures are the relevant organs at risk. We keep parotid gland mean dose below 26 Gy, and esophagus and trachea mean dose below 45 Gy. Buccal mucosa constraints are not as robustly established in the literature, but our institute's practice is to keep dose there within about 32 to 35 Gy without compromising target coverage, and to keep overall oral cavity dose below 45 Gy. We follow RTOG, QUANTEC, Timmerman, and more recently HyTEC and PENTEC guidelines for these constraints.

Question 8

What is the role of SBRT in early-stage lung and prostate cancer?

Dr. Garima Singh · Accepted Answer

For lung cancer, if the patient is operable, surgery is the treatment of choice. If a patient is medically inoperable due to comorbidity, we give SBRT, whether it is a primary early-stage lung cancer or a lung metastasis from elsewhere, such as breast cancer. Dose depends on tumour location: ultracentral tumours, close to the heart or mediastinum, get a more cautious regimen of around 60 to 70 Gy in 7 to 10 fractions; peripheral tumours can get 50 Gy in 5 fractions, or sometimes 55 Gy in 5 fractions. We follow established SBRT dose-constraint guidelines for all of this.

Radiation Oncology - Advances & Latest Trends

Questions Doctors Asked Dr. Garima Singh