Oropharynx

Oropharynx cancer is most often treated with definitive radiotherapy, with cisplatin added for more advanced disease. Most of these cancers are now HPV-related. The planning problem is a primary near the midline of the throat plus neck nodes, with both parotids, the swallowing muscles and the oral cavity close by.

Setup, dose levels and organ limits follow Head & Neck Planning Essentials. What is specific to the oropharynx — the base of tongue, tonsil, soft palate and posterior pharyngeal wall:

• Definitive radiotherapy is the usual approach. Surgery followed by radiotherapy is an alternative for some patients — see the post-operative page.
• Schedule. Commonly 70 Gy in 35 fractions with an SIB (63 and 56 Gy to the intermediate- and low-dose levels). For selected patients treated with radiotherapy alone, the same doses may be accelerated to finish in six weeks. 66 Gy may be considered for selected T1 tumors or after a diagnostic tonsillectomy with no residual gross disease.
• Concurrent chemotherapy. Radiotherapy alone for smaller tumors with limited nodes (T1–2 N0–1); chemoradiation for more advanced disease (T2–4 N1–2), with cisplatin — every three weeks or weekly — as the standard drug. In HPV-positive disease, cetuximab was inferior to cisplatin (RTOG 1016).
• HPV (p16) status is tested in every oropharynx cancer. It is a strong prognostic factor, but it does not change the planning approach in current protocols.
• One side or both. Both sides of the neck are usually treated. For well-lateralized tonsil or lateral pharyngeal wall cancers with limited nodes, treating only the involved side is recommended — which spares the opposite parotid and submandibular gland almost completely.

Uses the shared head and neck constraint table. The organs that usually decide an oropharynx plan:

• Parotids and submandibular glands — the contralateral glands are the main sparing opportunity, especially with one-sided treatment.
• Pharyngeal constrictors — often next to or inside the target; spare the parts outside it.
• Oral cavity — a normal structure here, so the non-oral cavity goal applies.
• Larynx and cervical esophagus — usually below the high-dose region and worth keeping low.
• Cochlea — matters more when cisplatin is given.