Heartburn isn't necessarily a sign of cancer, but it does need medical attention.
It's true that heartburn can be a symptom of esophagal cancer, but it doesn't follow that this is the cause of your indigestion. But chronic heartburn can certainly be a warning of gastroesophagal reflux disease (GERD), where stomach acid comes back up through the esophagus, causing pain.

If you have GERD, lifestyle changes - stopping smoking, avoiding indigestion triggers and so on - may help. Five per cent of those with GERD have a condition known as Barrett's esophagus, where stomach cells colonise the lower part of the esophagus. People who develop Barrett's esophagus do run a higher than usual risk of cancer. So if your heartburn doesn't improve with medication and lifestyle changes, you should certainly consult your doctor.