Larynx

Anatomy: Complicated!
Supraglottis = epiglottis, arytenoids and AE folds, false vocal cords, ventricle
True glottis = true vocal cords and anterior commissure
Subglottis = 5mm below free margin of true vocal cord extending down to the inferior border of cricoid
Staging system is slightly different for each subsite

Hoarseness: damage to several structures can lead to a hoarse voice
1) true vocal cord - even small/early lesions cause significant voice alteration
2) intrinsic muscles of larynx
3) cricoarytenoid muscle
4) recurrent laryngeal nerve - mediastinal tumors

Lymph node patterns of spread
~50% of patients are N0 at diagnosis
Levels II and III are most commonly involved
Clinically N0: ~20% will be found to have nodes in II and III if neck is dissected
N+: 50-60% in either II or III; 30% in IV

For true glottic cancers, nodal involvement is rare until the tumor grows outside the true cords
T1: risk of nodes approaches zero
T2: 2% have + nodes
T3-4: 20-30%

Types of laryngectomy
1) Total laryngectomy: removal of all laryngeal structures with pharyngeal reconstruction. Patients have a permanent tracheostomy and need voice prosthesis or learn esophageal speech. Typically performed for advanced lesions with irreversible laryngeal dysfunction.
2) Supraglottic partial laryngectomy: removes epiglottis, false cords, superior half of thyroid cartilage. This procedure is contraindicated in patients with lung disease since removal of the epiglottis results in chronic aspiration.
3) Supracricoid partial laryngectomy: removes true cords, false cords, entire cricoid cartilage, +/- epiglottis
4) Vertical hemilaryngectomy: removes one true cord, up to 1/3 of the opposite cord
5) Cordectomy: removal of only part of one true cord

RT alone for early stage cancers of the true glottis
Field extends from hyoid to cricoid and vertebral body to flashing the skin anteriorly
Fractionation is important in these patients
1) T1: Japanese trial randomized patients to 2Gy/day vs. 2.25Gy/day (PMID 16169681); total dose was 60 vs 56.25Gy for small lesions (involving less than 2/3 of the vocal cord) and 66 vs. 63Gy for larger tumors.  No effect was seen on survival but local control was better in the 2.25Gy arm (77 vs. 92%).
2) T2: same fields, different fractionation. Institutional retrospective data (MDACC) supports hyperfractionation. RTOG 9512 randomized to 70Gy in 35fx (2Gy/day) vs. 79.2Gy in 66 fx (1.2Gy b.i.d.).  This showed a strong trend (p = 0.07) to improved disease free survival in the hyperfractionated arm (57 vs 31%).  Local control was 79% for the hyperfx arm and 70% for the conventional arm with a p = 0.11.
3) T3N0: B/l neck nodal fields now need to be included, or neck dissection performed if the patient is having a laryngectomy. Role of chemotherapy and altered fractionation is controversial.

Locally advanced laryngeal cancer
Subsite no longer makes a difference
Laryngectomy is often performed if the larynx is already non-functional
Indications for adjuvant RT include thyroid cartilage invasion/T4 lesions, N2-3 disease, PNI or LVSI; chemo-RT indications are the same as they are anywhere in the head and neck (ECE, + margin)

Attempt at larynx preservation with concurrent chemoradiation is another option
Two famous laryngeal preservation trials have been performed

VA Larynx	RTOG 91-11
Any stage III - IV (T1N1 excluded)	Any stage III - IV (T1N1 excluded)
Induction chemo followed by RT vs. surgery followed by RT	RT only vs. concurrent CRT vs. induction chemo followed by RT

The VA larynx trial demonstrated that larynx preservation could be accomplished without compromising survival. In the RTOG trial, the highest rates of laryngectomy free survival were seen in the concurrent chemoradiation arm with overall survival equivalent among all arms (between 50-60% at five years).