How does cancer of the larynx (laryngeal cancer) affect the respiratory system?
According to this website:

http://www.spirometry.guru/fvc.html

it causes difficulty with inhalation but exhalation is normal...


  "Typically the expiratory part of the F/V-loop is normal: the
  obstruction is pushed outwards by the force of the expiration."
  "During inspiration the obstruction is sucked into the trachea with
  partial obstruction and flattening of the inspiratory part of the
  flow-volume loop."


the exact symptoms of a laryngeal tumor depends on where it is located on the larynx... above the vocal cords, on the vocal cords, or below the vocal cords...

but more generally:

anatomy: 
mouth/nose-->pharynx-->larynx-->trachea-->bronchi-->lungs

a tracheostomy may be necessary... basically the surgeon makes a connection between the skin outside the throat and the trachea... this bypasses the larynx (as well as pharynx and nose/mouth)...