National Marijuana Day on April 20th comes at a pivotal moment for pot lovers as more and more states are legalizing the once forbidden drug– and marijuana use is normalized like never before.

Some states like New Jersey and New York are taking more time to pass marijuana laws, while others with fewer issues and restrictions are moving forward more quickly to legalize. But many doctors and researchers are deeply concerned that we have not taken seriously enough research about marijuana’s effects on cancer risk and during cancer treatment.

According to some lung cancer doctors, marijuana smoking can cause aggressive lung cancer.

“As someone in the front lines who sees this every day, I’ve seen lung cancer caused by marijuana that is incredibly aggressive,” says Dr. Raja Flores, Chairman, Department of Thoracic Surgery at Mount Sinai Health System. “And just because we don’t have the numbers yet, because we haven’t been recording this data, doesn’t mean that marijuana is safe.”