CT scans on lungs

[ktex]

I just had my 2nd 6 month CT exam and noticed they haven’t been scanning my lungs. They only scan my pelvis/abdomen. I thought this was odd. I have a follow appointment in 3 weeks and will ask my oncologist about it but I’m curious if one of you knows if it’s common not to scan the lungs as well.

[roadrunner]

In general, I think the literature sets the risk of “skip” pulmonary metastases (lungs but not liver) at a relatively low level in a Stage 3 patient with colon—not rectal—cancer (which goes to the lungs first at roughly 2x the rate of colon cancer). That said, the risk, while comparatively low, is sometimes termed “significant” (this should be thought of in context, so more like 3% than 6% for all colon cancer vs. rectal cancer patients—though you are 3b, which likely increases risk somewhat from the broader context). Location (country), insurance considerations (if applicable), and your team’s protocol can be factors (you didn’t say where you are). Sometimes, however, you need to advocate for yourself to make certain the appropriate monitoring protocol is being followed in your case.

Overall, I would want at least some monitoring of the lungs for Stage 3b colon cancer. Thus, I would ask your team whether you should have it, and if not, why not? If they agree, you should ask what their perspective on the appropriate schedule is.

[CRguy]

I won't say a lot here ... BUTT ... you should probably be having some type of imaging on the lungs for a while.

my posts describing lymphatic/vascular drainage from the rectosigmoid to the chest

My lung met was picked up on survey Xray, not CT, SO ... just saying somebody should be doing some looking at your lungs !
IME ... IMO ... been there done THAT !

Cheers and best wishes
CRguy

[rp1954]

I think there are several issues about risks and costs.

One article that referenced NCCN 4.2020 on stage II/III colon cancer, recommended a CT chest scan for lungs every 12 months.

Of course many insurers would like to skimp and influence drs in their networks.
What's your insurance situation, especially insurer type and out of pocket cost?

Risks?
Radiation
Figure a CT scan vs plain xray or pair is 50 - 250 times more radiation. Small but non zero risk.

Undetected mCRC ,
finding the first met anywhere sets the stage....
Dr's and insurers wrangle over sensitivity, specificity, false negatives and false positives but I'm not seeing cur rent US literature on plain x-rays for CRC. In developing countries plain xray is often the starting point. Perhaps an insurer will offer it without deductible.

Skipping over a lot. If low risk stage 3 patient lung met is a hypothetical 7% and some or most mCRC cases are picked up with pelvic mets too, what's the net % exposure?
Then you might have a choice of instruments with different sensitivities
Plain Xray. Vs single detection CT vs multispectral CT.
Throwing hazy numbers at the wall let's say 62% vs 71% vs 75% sensitivity some years ago
Of you might have a radiologist screwup and simply miss something, like our CT#2.
(being suspicious of an escalating CEA series I got an outside second reading)

I'm similar to CRguy I'd get something, especially a first scan, to at least get some cover for most of any mets, and the "Oh my god" case.