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Incheon cancer registry

The Incheon cancer registry was established in October 1997 at the College of Medicine, Inha University, Incheon. Data collection on incident cancer cases started retrospectively to include cases from the beginning of 1997. The registry is rather new, and its data were included in the volume IX of the quinquennial IARC publication Cancer Incidence in Five Continents^[1]. Cancer is not a notifiable disease, hence registration of cases is done by active methods. The principal sources of information on cancer cases are the records in more than 100 medical institutions, comprising hospitals in public and private sectors, pathology laboratories, radiation and imaging centres in and around Incheon. The registry covers an area of 986 km² and caters to an entirely urban population of about 2.6 million with a sex ratio of 980 females to 1000 males in 2004. The average annual age-standardized incidence rate (ASR) is 265 per 100 000 among males and 165 per 100 000 among females, with a lifetime cumulative risk of one in 4 of developing cancer in the period 1997–2002. The common age-standardized incidence rate of cancers among males are stomach (62), lung (50) and liver (37),and among females are breast (25), stomach (23) and cervix (20).

Map. Map showing location of Incheon, Republic of Korea Click here to open map (PDF format)

The registry is contributing data on survival from 42 cancer sites or types registered during 1997–2001 for the first time in this volume of IARC publication on Cancer Survival in Africa, Asia, the Caribbean and Central America.

Data quality indices

The proportion of cases with histologically verified cancer diagnosis in the series is 71%, varying from 16% (cancer of the uterus unspecified) to 100% (Hodgkin lymphoma). The frequency of cases registered on the basis of a death certificate only (DCOs) is 8%, ranging between nil in many cancers and 51% in uterus unspecified cancer. Cases excluded without any follow-up are negligible. Thus, 49–100% of the total cases registered are included in the estimation of the survival probability.

Table 1. Data quality indices - Proportion (%) of histologically verified and death certificate only cases, number and proportion of included and excluded cases by site, Incheon, Republic of Korea, 1997–2001 cases followed-up until 2002 Click here to open table (PDF format) Click here to open comparative statistics by registry

Outcome of follow-up

Follow-up information has been obtained predominantly by passive methods. These included obtaining cancer mortality information from the death certificates in vital statistics section. The mortality data are periodically matched with the incident cancer database using the national identity number. The vital status of the unmatched incident cases is also ascertained by review of medical charts. However, all incident cases for whom death information is not available were presumed to be alive on the last date of the year for which the mortality data are fully utilized for matching.

The closing date of follow-up was 31^st December 2002. The median follow-up ranged from 1 month in unspecified uterus cancer to 44 months for Hodgkin lymphoma.

Table 2. Number and proportion of cases by vital status and median follow-up (in months) by site, Incheon, Korea, 1997–2001 cases followed-up until 2002 Click here to open table (PDF format) Click here to open comparative statistics by registry

Survival statistics

All ages and both sexes together

The top-ranking cancers on 5-year relative survival are testis (98%), thyroid (92%), corpus uteri (84%), non-melanoma skin and ureter (83%). The lowest survival rate is encountered with pancreatic cancer (12%) preceded by unspecified uterus (15%), liver (16%), lung (18%) and gallbladder (20%). Salivary gland (69%) and nasopharynx (56%), among other head and neck cancers, and colon and rectum (55%), among gastrointestinal cancers, have higher survival than others. Survival from cancers of the urinary system is 71% in urinary bladder and 67% for kidney. Hodgkin lymphoma had a better survival (83%) than non-Hodgkin (54%). The survival figures for leukaemias are lymphoid (51%) and myeloid (40%).

The 5-year age-standardized relative survival (ASRS) probability for all ages together is generally less than or similar to the corresponding unadjusted one for a majority of cancers. Also, the 5-year ASRS (0–74 years of age) is generally higher than or similar to the corresponding ASRS (all ages) for a majority of cancers.

	Table 3. Comparison of 1-, 3- and 5-year absolute and relative survival and 5-year age-standardized relative survival (ASRS) by site, Incheon, Republic of Korea, 1997–2001 cases followed-up until 2002 Click here to open table (PDF format) Click here to open comparative statistics by registry
	Figure 1a. Top ten cancers (ranked by survival), Incheon, Republic of Korea, 1997–2001 Click here to open figure (PDF format) Click here to open graph for all the cancer sites

Sex

Table 4a. Site-wise number of cases, 5-year absolute and relative survival by sex, Incheon, Republic of Korea, 1997–2001 cases followed-up until 2002 Click here to open table (PDF format) Click here to open comparative statistics by registry

Male

The 5-year relative survival is distinctly higher in cancers of the tongue, other thoracic organs, non-melanoma skin, peritoneum, ureter, bladder and Hodgkin lymphoma among males than females.

Figure 1b. Top five cancers (ranked by survival), Male, Incheon, Republic of Korea, 1997–2001 Click here to open figure (PDF format) Click here to open graph for all the cancer sites

Female

The 5-year relative survival estimates for cancers of the breast, cervix and ovary are 79%, 79% and 60%, respectively. The survival is notably higher among females than males in cancers of the oral cavity, salivary gland, tonsil, nasopharynx, hypopharynx, small intestine, nose/sinuses, skin melanoma, adrenal gland, non-Hodgkin lymphoma, multiple myeloma and myeloid leukaemia.

Figure 1c. Top five cancers (ranked by survival), Female, Incheon, Republic of Korea, 1997–2001 Click here to open figure (PDF format) Click here to open graph for all the cancer sites

Age group

The 5-year relative survival by age group reveals an inverse relationship: a decreasing survival with increasing age at diagnosis in cancers of the stomach, small intestine, colon, gallbladder, larynx, lung, breast, cervix and ovary. For other cancers, no pattern on the survival by age group is forthcoming.

Table 4b. Site-wise number of cases, 5-year absolute and relative survival by age group, Incheon, South Korea, 1997–2001 cases followed-up until 2002 Click here to open table (PDF format) Click here to open comparative statistics by registry

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References

1. Curado MP, Edwards B, Shin HR, Storm H, Ferlay J, Heanue M and Boyle P. Cancer Incidence in Five Continents, Vol. IX, IARC Scientific Publications No. 160. IARCPress, Lyon, IARC.
   (link to CI5)