Kolorektální karcinomy v Japonsku

Súhrn

Incidence kolorektálního karcinomu v Japonsku stoupá. Bylo zjištěno, že nárůst frekvence výskytu je vyšší u karcinomu tlustého střeva než u karcinomu rekta. Studie ukazuje proximalizaci místa nádoru z levé do pravé části tlustého střeva. Je též zcela zřejmý posun k časnějším stadiím onemocnění. Na základě rozsáhlých resekcí lymfatických uzlin je patrné, že v průběhu doby došlo ke zlepšení frekvence celkového pětiletého přežití z 55 % na 69 %.

Colorectal cancer incidence has been on the increase in Japan and was estimated in 1996 to be approximately 80,000 with more than fourfold in crease during the past 20 years. This cancer is the fourth and the second leading cause of death for males and females respectively and approximately 36,000 patients died of this cancer in 2001.

According to the GLOBOCAN 2002 report by the International Agency for Research on Cancer, the countries with the highest incidence of colorectal cancer are shown in figure 1. In males, the Czech Republic is the highest, and Japan is fifth. In females, the Czech Republic is tenth and Japan is 22^nd (figure 1) [1].

We established “Japanese General Rules for Clinical and Pathological Studies on Cancer of the Colon, Rectum and Anus” in 1977 [2]. At that time the TNM classification had not been established and Dukes classification had been prepared. Since 1978 we have registered all cases of colorectal cancer in whole country. From this registration database, 84,695 patients who had surgery were analyzed [3].

Changes in tumor sites

Changes in tumor sites have been observed over the last 20 years. The number of registered cases of colon and rectal cancer, colon is light blue line, rectum is pur-pure line, increased in both males and females.

The rate of colon cancer, compared with rectal cancer, increased in both males and females, orange colored circle in the figure 2 and the predominance of colon cancer was especially noticeable in females (figure 2).

Proximal migration of the tumor

Proximal migration of the tumor site was noted. While the proportion of rectal cancer, red colored in the figure 3, was on the decline, the proportion of right colon cancer, orange colored, and left colon cancer, blue colored, continued to increase steadily. In females the number of right colon cancers exceeded that of left colon cancers during the most recent period (figure 3).

Distribution of TNM stage

The distribution of TNM stages is shown in figure 4. The proportion of stage 3 and 4 decreased as expected. The striking changes were for stage 1. 12%, 15%, 18% and 21%. The proportion of stage 1 nearly doubled from 12% to 21%.

Magnifying colonoscopy with the dye-spray method

Recently, with the progress in colonoscopic diagnosis, we are able to make fairly accurate diagnosis of T-1 cancer. Using magnifying colonoscopy with the dye-spray method, we can observe the surface of the tumor in minute detail [5]. The upper row photographs show a flat in normal view, but in lower row elevated lesion which is clearly identified by this dye-spray method (figure 5).

These photos in figure 6 show the findings of magnifying colonoscopy. This is normal view, next dye-spray view. Magnifying slowly to the surface, we can see fine pits like this, and this is magnifying pits. And the scope is capable of magnifying 100 times for detailed observation.

Pits pattern of surface structure

Surface structure can be classified into 6 patterns (figure 7) [6]. Type 1, round pits, is normal or inflammatory. Type 2 papillary pits, is hyperplasia. Type 3L, large tubular pits, is adenoma. Type 3S, small tubular pits, is adenoma. Type 4, branch like pits, is villous tumor. Type 5, non-structure pits, is cancer. Non-structural type is an indicator of massive invasion of the submucosal layer. By these techniques we can find small cancers of large bowel.

General rules of dissection of extent lymph nodes

Concerning surgery, we surgeons, have to dissect the radical extent lymph nodes according to “The general rules for clinical and pathological on cancer of the colon and rectum”. Regional lymph nodes are classified into three categories such as paracolic node, intermediate nodes, and main nodes. The extent of D-2 resection is to the paracolic (n 1) and intermediate nodes (n 2), and that of D-3 resection is to all three nodes categories (n 1, n 2, n 3) in figure 8.

The percentage of nodal involvement and survival

According to the registered data, the percentage of nodal involvement is shown in the figure 9. In T3 and T4 cancer, the positive rate for para-colic nodes (n 1) was 29%, intermediate nodes (n 2) was 15.3% and main nodes (n 3) was 4.2%.

As you see survival of colon cancer according to nodal dissection, survival analysis comparing D3 and D2 resection shows that survival rates of patients who had D3 resection were significantly better than those who had D2 resection (figure 10). Based on these results, D3 resection should be the standard surgery for stage 2 or stage 3.

Survival rates of colorectal cancer patients

The most important trend of these data was the improvement in survival rates of patients with rectal cancer and colon cancer. The over all survival rates of the four time periods were compared. All survival curves were separated from each subsequent period by statistically significant differences (figure 11). The 5-year survival rate increased from 55% to 69%.

_DISCUSSION

Proximal migration of colon and rectum cancer already has been noted not only in western countries but also in non-white population. In our database of the Japan Society for cancer of the Colon and Rectum (JSCCR) registry, the rate of colon cancer compared with rectal cancer, increased in both males and females. The migration of colon cancer from the left side colon to right side colon was noted [4]. The impact of newer diagnostic techniques including total colonoscopy and real increase are proposed in possibilities. The prevalence of proximal colon cancer was significantly higher in females than males. No body knows the reason why right side colon cancer is shown higher in females than males.

Using magnifying colonoscope with dye-spray method, we can find the earlier stage cancer of the colon and rectum. According to this progress, the distribution of TNM stage has changed and as for stage 1, the proportion of stage 1 nearly doubled in 2000. Especially by magnifying colonoscope, pits patterns of the surface of tumors are classified into 6 patterns, non-structured type pits is cancer. By this technique very small cancer of the colon can be found.

Concerning surgery for colon and rectal cancer, we, Japanese surgeons do lymphadenectomy according to “the general rules for clinical and pathological on cancer of the colon and rectum”. As the survival curve showed, D3 resection should be standard surgery for cancer of the colon in stage 2 or stage 3.

Prof. Morito Maruta M.D., Ph.D.

Sankeikai Hattori Hospital 1–3–20 Sawakami

Atsuta-ku

Nagoya 456-0012

Japan