Chapter 26: Cancer survival in Chiang Mai, Thailand, 1993-1997

Suwanrungruang K, Vatanasapt P, Kamsa-Ard S, Sriamporn S and Wiangnon S

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Abstract

The Khon Kaen cancer registry was established in 1984 as a hospital-based cancer registry, and population-based cancer registration started in 1988 with retrospective data collection from 1985. Cancer registration is done by passive and active methods. Data on survival for 13 cancer sites or types registered during 1993–1997 were reported. Follow-up was done by active methods, with median follow-up ranging between 8–32 months for different cancers. The proportion with histologically verified diagnosis for various cancers ranged between 54–100%; death certificate only cases (DCOs) comprised 0–5%; 85–97% of total registered cases were included for survival analysis. Five-year follow-up ranged from 40–83%. Five-year age-standardized relative survival rates for common cancers were cervix (58%), breast (61%), colon (39%), ovary (43%), non-Hodgkin lymphoma (42%) and rectum (43%). Five-year relative survival by age group portrayed an inverse relationship or was fluctuating. Five-year survival was the highest for localized disease, followed by the regional and distant metastasis categories. Trends in 5-year relative survival in 1993–97 compared to 1985–92 showed a marked increase for cancers of the rectum, breast, ovary, Hodgkin and non-Hodgkin lymphomas and decrease for cancers of the lip and larynx.


Khon Kaen cancer registry

The Khon Kaen cancer registry was established in 1984 as a hospital-based cancer registry at the Faculty of Medicine, Srinagarind Hospital, Khon Kaen University. Population-based cancer registration started in 1988 with retrospective data collection from 1985, and the registry has been contributing data to the quinquennial IARC publication Cancer Incidence in Five Continents since Vol VI[1]. Cancer registration is done by both passive and active methods. The principal sources of information on cancer cases are the hospital and pathology records. The registry covers an area of 10 866 km2 and caters to a mixed urban and rural population of about 1.6 million with a sex ratio of 1008 females to 1000 males in 1995. The average annual age-standardized incidence rate is 179 per 100 000 among males and 128 per 100 000 among females, with a lifetime cumulative risk of one in 6 of developing cancer for both sexes in the period 1993–1997. The top-ranking cancers among males are liver, lung and colon, among females, the order is liver, cervix and breast.

Map. Map showing location of Khon Kaen, Thailand

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The registry contributed data on survival from 33 cancer sites or types for the first volume of the IARC publication on Cancer Survival in Developing Countries[2]. In the present volume, data on survival from 13 cancer sites or types registered during 1993–1997 are reported.

Data quality indices

The proportion of cases with histologically verified cancer diagnosis in this series is 77%, varying between 100% for the lymphomas and 54% for colon cancer. The proportion of cases registered as death certificate only (DCOs) is 2%, ranging between nil for many cancers and 5% for cancer of the cervix. Cases excluded without any follow-up constitute 7%. The exclusion of cases from the survival analysis is the greatest among those with cancer of the cervix (15%) and the least among rectal cancer (3%). Thus, 85–97% of the total cases registered among selected cancers 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, Khon Kaen, Thailand, 1993–1997 cases followed-up until 2000

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Outcome of follow-up

Follow-up has been carried out predominantly by active methods. These include abstraction of cancer mortality from death certificates with a mention of cancer from the office of the Ministry of the Interior. Death certificates in remote villages are filled in by the headman of the village and are sent to the registry. The data collected are matched with the incident cancer database. The vital status information of the unmatched incident cases is obtained by repeated scrutiny of records in the hospitals, postal enquiry and house visits.

The closing date of follow-up was 31st December 2000. The median follow-up time ranged between 8 months for cancer of the urinary bladder to 32 months for lip cancer. Complete follow-up information at five years from the incidence date ranged from 83% for rectal cancer to 40% for cancer of the cervix. The proportion of cases lost to follow-up was generally the highest within one year from the incidence date.

Table 2. Number and proportion of cases with complete / incomplete follow-up and median follow-up (in months) by site, Khon Kaen, Thailand, 1993–1997 cases followed-up until 2000

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Survival statistics

All ages and both sexes together

The 5-year relative survival is the highest in Hodgkin disease (69%) and the lowest in tongue cancer (30%). Among head and neck cancers, the survival figures are lip (63%), oral cavity with tongue excluded (39%), nasopharynx (33%) and larynx (34%). The survival is similar for colon and rectal cancers (43%). Non-Hodgkin lymphoma has a relative survival of 40% at 5 years from incidence date.

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 most 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, Khon Kaen, Thailand, 1993–1997 cases followed-up until 2000

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Figure 1a. Top ten cancers (ranked by survival), Khon Kaen, 1993–1997

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Sex

Table 4a. Site-wise number of cases, 5-year absolute and relative survival by sex, Khon Kaen, Thailand, 1993–1997 cases followed-up until 2000

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Male

The top ranking cancers on the basis of 5-year relative survival are Hodgkin lymphoma (71%), cancers of the urinary bladder (65%), lip (63%) and rectum (42%), and non-Hodgkin lymphoma (38%).

Figure 1b. Top five cancers (ranked by survival), Male, Khon Kaen, 1993–1997

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Female

The top five cancers ranked on 5-year relative survival are Hodgkin lymphoma (69%), breast (62%), lip and bladder (60%), ovary (59%) and cervix (54). Survival is distinctly higher among females than males for cancers of the tongue, oral cavity, nasopharynx and colon.

Figure 1c. Top five cancers (ranked by survival), Female, Khon Kaen, 1993–1997

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Age group

The 5-year relative survival by age group reveals an inverse relationship, a decreasing survival with increasing age at diagnosis, for lip cancer. In the rest, it is observed to be fluctuating.

Table 4b. Site-wise number of cases, 5-year absolute and relative survival by age group, Khon Kaen, Thailand, 1993–1997 cases followed-up until 2000

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Extent of disease

The proportion of cases by extent of disease among breast cancer is 5% localized, 42% regional and 21% distant metastasis. The corresponding figures for cancer of the cervix are 17%, 54% and 6%, respectively. Ovarian cancer is represented equally by cases with localized and distant metastatic disease. The extent of disease is unknown in 19–32%. The 5-year absolute survival by extent of disease follows the expected pattern: highest for localized cases followed by regional and distant metastasis cases among known categories of extent of disease.

Table 5. Proportion (%) of cases and 5-year absolute survival by extent of disease and site, Khon Kaen, Thailand, 1993–1997

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Figure 2a-2c. Absolute survival from selected cancers by extent of disease: Khon Kaen, Thailand: Cancer of the breast

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Figure 2a. Absolute survival by extent of disease: Khon Kaen, Thailand: Cancer of the breast

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Figure 2b. Absolute survival by extent of disease: Khon Kaen, Thailand: Cancer of the cervix

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Figure 2c. Absolute survival by extent of disease: Khon Kaen, Thailand: Cancer of the ovary

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Survival trend

The 5-year relative survival for cases registered in 1993–1997 compared to those in 1985–1992[2] shows a marked increase in cancers of the rectum, breast, ovary, Hodgkin and non-Hodgkin lymphomas. A decrease in survival in the corresponding period is observed for cancers of the lip and larynx. For the rest, the absolute difference in survival is <10 percent units.

Table 6. Comparison of 5-year absolute and relative survival of cases diagnosed between 1985–1992 and 1993–1997, Khon Kaen, Thailand

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References

  1. Parkin DM, Whelan SL, Ferlay J and Storm H. Cancer Incidence in Five Continents, Vol I to VIII: IARC Cancerbase No. 7. IARCPress, Lyon, 2005.
    (link to CI5)

  2. Vatanasapt V, Sriamporn S, Kamsa-Ard S, Suwanrungruang K, Pengsaa P, Charoensiri DJ, Chaiyakum J and Pesee M. Cancer survival in Khon Kaen, Thailand. In: Cancer Survival in Developing Countries (eds) R Sankaranarayanan, RJ Black and DM Parkin. International Agency for Research on Cancer, IARC Scientific Publications No. 145, Lyon, 1998, pp 123-134.
    (link to Cancer Survival, volume 1)