xRead - Nasal Obstruction (September 2024) Full Articles

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KUANetal.

Elective treatment of the N0 neck and avoidance of radiating lower neck lymphatics in NPC

developed grade 3 late toxicities, while grade 2 xerosto mia was noted in 26%, 12%, and 9% at 1, 2, and 3 years after starting IMRT, respectively. Prospective randomized studies on adaptive radiotherapy aiming at identification of patient, dosimetric, radiomics, and biological triggers of adaptive radiotherapy are warranted to determine the selection criteria for adaptive radiotherapy. Role of adaptive radiation therapy in treatment of NPC

Aggregate grade of evidence

B (Level 1: one study; Level 2: one study)

Benefit

Omitting the uninvolved lower neck lymphatics may reduce the short- and long-term toxicities of RT without jeopardizing survival. Potential increase in nodal failure and worsening of survival outcomes. May need multiple investigations including MRI and PET/CT to confirm the extent of nodal metastasis. No direct cost analysis available. Patients should be counseled about the extent and field of neck radiation as it relates both to disease control and toxicity/side effects. Potential benefit in toxicity reduction may be negated by increase in treatment failures. Balance of benefits and harms

Harm

Aggregate grade of evidence

C (Level 2: one study; Level 3: one study)

Cost

Benefit

Adjustment of the radiation field to account for change in tumor size and patient anatomy, theoretically improving tumor contouring and reducing unnecessary radiation to surrounding critical structures. Increased cost. Increased complexity of treatment delivery. Potential undertreatment of tumor. Increased cost due to mid-treatment imaging and increased labor cost due to the need for replanning. No economic studies available. Promising concept but not enough data to conclude. Potential benefit in reducing marginal miss and unnecessary radiation to critical structures. Prospective trials should be designed to identify patient groups and disease factors that would benefit from adaptive radiotherapy. Balance of benefits and harms.

Benefits–harm assessment

Value

Harm

judgments

Cost

Policy level Option. Intervention Patients may be able to avoid RT to the

Benefits–harm assessment

uninvolved lower neck lymphatics if MRI and PET imaging modalities confirmed the absence of cervical nodal metastasis or nodal disease limited to one side of the neck.

Value

judgments

7 Adaptive radiotherapy Adaptive radiotherapy is based on the principle of adjust ing radiation as treatment progresses, to account for changes in tumor volume and patient anatomy that occur during treatment. Retrospective studies have demon strated dosimetric and clinical advantages of adaptive radiotherapy in NPC, including reduced tumor volumes, better sparing of SARs, and improved patient-reported outcomes. 1675 There are few prospective studies on pre planned adaptive radiotherapy for NPC. A phase III RCT compared sequential IMRT to IMRT with simultaneous integrated boost (SIB) to the high-risk and low-risk plan ning target volumes. The trial showed similar 3-year OS (86.3% vs. 83.8%; p = 0.938), 3-year PFS (72.7% vs. 73.4%; p = 0.488), and grade 3/4 acute toxicities. However, there was a trend toward significantly higher late toxicities with SIB (12.1% vs. 4.9%; p = 0.062). 1676 More recently, a Japanese phase II single-arm study of 75 patients of stage II–IVB NPC treated with an adaptive IMRT plan after 46 Gy/23 fractions for a total of 70 Gy/35 fractions demon strated a 3-year OS of 88% and PFS of 71%. 1677 Fifteen (20%)

Policy level Option. Intervention Adaptive radiotherapy for NPC may have an

emerging role given its ability to improve QOL, though this must be balanced with the risk of undertreatment.

8 Role of proton therapy Newer radiation modalities like proton or carbon ion ther apy have a theoretical advantage in treating NPC especially in locally advanced tumors where the tumor is close to crit ical structures like brainstem or optic chiasm. However, at the time of writing, proton or carbon ion therapy is still not widely available and no major phase III trials have been conducted to compare the efficacy of proton therapy to standard IMRT. A meta-analysis on the available retro spective studies and phase II trials on the use of proton and carbon ion therapy for treatment of NPC showed no difference in 2-year survival outcome but a significantly lower rate of tube feeding and mucositis. 1678 Proton ther apy has nonstatistically significant improvement in acute