The shrapnel was from the 2nd Tet battles in May '68, I made it thru the first Tet battle untouched even in the Saigon Cholon battle to kick the VC out of Saigon. You're right, for some reason the tumors pick the metal to encompass to protect the other tissues. but cause more problems themselves. The one good thing the tumor in the leg caused was the VA for the next year watched the shrapnel in my lung a little closer to make sure the body wasn't growing anything around it, but after a year they stopped monitoring it too. For as big an outfit as the VA is with whole departments devoted to scheduling, you would think that would be an area they excel in, but nope, it isn't.
you might also want to use the MYHealthvet.gov. Get a user ID if you don't have one. gives you access to all your records including scheduled appointments, what I discovered are the errors, where they had me scheduled for something and never notified me of that appointment and then when I didn't arrive for the appointment that I didn't know about, put in an entry that I failed to make the scheduled appointment. A lot of guys have found entries like that. I spent 3 months compairing my records with the VA's documentation and developed a long and detailed doucment showing in detail, how screwed up their doucments and process was for me. I shared that with my sentor and congressman. My point is they may have not just givin up on monitoring you, but failed to notify you of appointments and if you miss three scheduled appointments, you get dropped. I made them correct every error in my file and screamed, shouted, and threatended them, one of the benefits of PTSD, that if they didn't I'd make them wish they had. Yea, I was there from November 67 through May 69. Tet, I was at Lang Vei, 5th Special Forces camp 101, they over ran us, with those tanks that they didn't have. Unfortunitly our fall back position was a Marine fire base about 15 miles east of Lang Vei, called Khe Sanh. I was lucky, I was one of the medics and wounded and our skipper ordered me to Khe Sanh with the first bunch of wounded orther wise I'd be dead.