Can "excessive" burping be a symptom of anything serious??

Recently I've noticed that my dad has been burping more than normal. He has always burped a lot, but I don't understand how he just burps randomly without having just eaten or drank anything. It worries me immensely because I was looking online and found that people with cancer burp a lot. I found that one person said that her dad had been burping more than normal before he was diagnosed with esophageal cancer. My dad doesn't complain about the burping, it's just something that I have noticed. He gets a little bit of heartburn after eating certain foods, and when he lays in bed at night he clears his throat several times. He doesn't experience any pain, but is this a symptom of anything serious? I was even looking at the symptoms for lung cancer and they said online that constantly clearing throat and burping is a symptom of it. I am really worried, even though my dad says he doesn't have any pain at all and burping/clearing throat doesn't bother him. Is this something to be worried about? I wish he would go to the doctor but he says it's ridiculous to go to the doctor for burping and clearing throat. He says that sometimes he clears his throat out of habit as well. Please help me!! Should I be concerned?

Also, what is "excessive burping"? He burps a good 20 times a day. To me this seems like a lot since it's rare for me to even burp once a day!

I know this may be a silly question, but I keep finding things online that worry me.