Curiosity Question

I was told the same thing, that the majority of recurrance (and maybe mets showing up) was in the first two years.  The number I was told was 80-85%  I was really Stage IV from the beginning, though the met on the lung was too small to tell.  I am not sure if the number was based on Stage III or Stage IV though.

I had some other studies I think at one point (this was a couple of years ago, could not find them) which mentioned the 80/85% in two years, but could not find them now. One below mentioned 60%, and some other information.  The footnote referenced in the second study below has a bit of breakdown based on staging.

http://www.cancerjournal.net/article.asp?issn=0973-1482;year=2016;volume=12;issue=4;spage=1257;epage=1260;aulast=Yazilitas

"Results: Of 250 patients, 151 (60.4%) (Group 1) were relapsed within the first 24 months after completion of the primary therapy and 105 (39.6%) were relapsed later than 24 months. The patients with T1–T2 and Grade I tumors were relapsed in late period (P < 0.05). The rates of administered systemic chemotherapy and targeted therapies after relapse were similar in both groups. The median overall survival rates in patients relapsed within the first 24 months and after 24 months were 18 months and 21 months, respectively (P = 0.05).

Conclusions: In patients with CRC, the time duration of relapse after completion of the operation and adjuvant chemotherapy was a prognostic factor. Grade I and superficial tumors (T1–T2) are the predictors of late relapses (after >24 months). The patients relapsed within the first 24 months after primary therapy had poor prognosis compared to those who relapsed in late period."

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4868559/

"Recurrent disease usually presents as distant metastasis in the liver or lungs or as locoregional recurrence in the pelvis or peritoneum. Also the risk of second colorectal malignancy is increased. Most recurrences happen during the first 2 to 3 years after initial treatment.3–5"

From study in FN 3 

"Of the 5671 colorectal cancer patients, 1042 (18%) were diagnosed with metachronous metastases. Most common affected sites were the liver (60%), lungs (39%), extra-regional lymph nodes (22%), and peritoneum (19%). 86% of all metastases was diagnosed within three years and the median time to diagnosis was 17 months (interquartile range 10-29 months). Male gender (HR=1.2, 95%CI 1.03-1.32), an advanced primary T-stage (T4 vs. T3 HR=1.6, 95%CI 1.32-1.90) and N-stage (N1 vs. N0 HR=2.8, 95%CI 2.42-3.30 and N2 vs. N0 HR=4.5, 95%CI 3.72-5.42), high-grade tumour differentiation (HR=1.4, 95%CI 1.17-1.62), and a positive (HR=2.1, 95%CI 1.68-2.71) and unknown (HR=1.7, 95%CI 1.34-2.22) resection margin were predictors for metachronous metastases.""

I had created this spreadsheet for my own use (3b) a while back.  I did not save the reference of the study upon which  I based it, and I am getting ready to go away this weekend, so I do not have the extra time to re-reseach it, so this is from the "for what it's worth" category:

Year    Cumulative recurrence   Single year recurrence
1                      27.50%                27.50%
2                      57.50%                30.00%
3                      74.60%                17.10%
4                      85.50%                 0.90%
5                      89.60%                 4.10%

In my recollection, my peak chance of recurrence was at 21 months.  Of course, there is always the caution about the problem with statistics.

The odds also vary with different mutations and treatments, like KRAS or BRAF mutants, and different treatment chemistries