Acid reflux can lead to cancerous growths.
More info: Having acid reflux does not mean that you will develop cancer, but persistent, severe acid reflux can increase the risk factor.
Gastro-Esophageal Reflux (GER)?
Acid reflux, also known as GER (gastro-esophageal reflux), begins when stomach acid rises up with food. The digestive juice, or acid, may irritate the lining of the esophagus, which is the tube that carries food from the mouth to the stomach. This irritation is exhibited by a burning sensation felt in the throat or chest of the affected person. However, children under twelve years of age with GER may not experience heartburn, but instead exhibit vomiting, coughing, and respiratory problems.
Gastro-Esophageal Reflux Disease (GERD)
On-going (more than twice per week) acid reflux, can be classified as acid reflux disease, otherwise known as GERD (gastro-esophageal reflux disease). Inevitably, persistent GERD can cause scar tissue to form as a result of the burning stomach acid coming up into the esophagus.
Esophageal Cancer and GERD
Cancer of the esophagus in not common in the US occurring in 1 in 125 men and 1 in 435 women. 
It occurs when the DNA in the cells of the esophagus mutate. These mutated cells grow and divide forming tumors. Though it is not clear exactly what causes esophageal cancer, it is believed that constant irritation to the lining of the esophagus may contribute to its development. Risk factors include drinking alcohol, tobacco use, drinking very hot liquids, and GERD.  The risk factor for developing cancer increases with the severity and longevity of the GERD. 
Barrett’s Esophagus AND GERD
When acid refluxes into the lower portion of the esophagus over an extended period, it can damage the squamous cells of the lining. These cells are then replaced by gland cells like those of the lining of the stomach and intestines, a condition called Barrett’s esophagus. Ten to fifteen percent of people with GERD develop the condition. 
The abnormal gland cells of Barrett’s esophagus can change over time leading to dysplasia, which is a precancerous change in the tissue. Dysplasia increases the risk of cancer. 
Laryngeal and Pharyngeal Cancer
Though it is widely accepted that GERD is a risk factor for the development of esophageal cancer, the association between GERD and cancer of the larynx and pharynx is not so clear. The larynx is the portion of the throat that contains the vocal chords, the pharynx connects the mouth to the esophagus. Several studies have concluded that patients with these types of cancer have a higher rate of GERD. One study identified GERD and smoking as an increased risk factor of laryngeal cancer. 
A separate study found no such association. 
Severe GERD Needs to Be Monitored Closely
Because of the side effects, people who have GERD, or experience symptoms of GERD, need to be followed closely by a physician. A physician may put a treatment plan in action to prevent cancer from occurring.
A treatment plan may involve life-style changes, medications, and/or surgery. Life-style changes may include the following: stopping smoking, avoiding acid producing foods and beverages, losing weight if needed, wearing comfortable clothing (not tight), eating two-three hours before lying down, and sleeping with your head elevated. Medications and/or surgery may not be necessary if life-style changes alone prove effective.
 American Cancer Society
What Are the Key Statistics about Cancer of the Esophagus
 Mayo Clinic
  American Cancer Society
What Are the Risk Factors for Cancer of the Esophagus?
 American Society for Gastrointestinal Endoscopy
GERD, Barrett’s Esophagus and the Risk for Esophageal Cancer
 Journal Watch
Does GERD Increase Risk for Laryngeal Cancer?
 Cancer Epidemiology Biomarkers and Prevention; Nilsson M
No association between gastroesophageal reflux and cancers of the larynx and pharynx.
2005; Volume: 14; No:5; Pages: 1194-1197