I've had a lump under the skin of my penis shaft for roughly 5 plus years. should i be concerned about cancer or anything serious? it's more visible when erect and hasn't growed?

Likely a cyst: It is likely to be a sebaceous cyst. It would be advisable to get it removed, though it is not an urgent matter. Have a healthy diet, exercise 30 minutes/day, drink plenty of water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. For nutrition: http://www.choosemyplate.gov/. Get HPV and Covid vaccines. Wish you good health!