According to Egyptian-based media, the powerful explosion near the medical facility was caused by the detonation of an oxygen cylinder that was inside of a car that collided with another vehicle in the centre of the city.
The explosion reportedly caused a blaze and dozens of fire trucks were sent to the scene to extinguish the flames. Emergency services are reportedly still working at the scene of the accident.
The vehicle reportedly belonged to one of the staffers at the institute.The blast happened when a car driving against traffic on Cairo's Nile corniche road collided with three other cars, the interior ministry said in a separate statement.
It triggered a blaze that forced the partial evacuation of the nearby National Cancer Institute, the health ministry said.
Local media reported earlier on Monday that at least 8 people had been killed due to the explosion.
There was no official statement indicating that the explosion was an attack.
Egypt's public prosecutor is investigating the cause of the incident, sources told Reuters, but there was reportedly no official statement issued indicating that the explosion was an alleged attack.