Chapter 28: Cancer survival in Songkhla, Thailand, 1990-1999
Sriplung H and Prechavittayakul P
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The registry is contributing data on survival from 36 cancer sites or types for the first time in this volume of the IARC publication on Cancer Survival in Africa, Asia, the Caribbean and Central America.
The closing date of follow-up was 31st December 2003. The median follow-up ranged from 3 months for liver cancer to 71 months for thyroid cancer. Complete follow-up information at five years from the incidence date ranged from 85% for myeloid leukaemia to 50% for non-melanoma skin cancer. The losses to follow-up occurred evenly in all the time periods of <1 year, 1–3 years, 3–5 years and >5 years and are ascertained to be random.
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.
Abstract
The Songkhla registry, besides being hospital-based, has population-based cancer registration data available since 1990. Cancer registration is done by active methods. The registry is contributing data on survival for 36 cancer sites or types registered during 1990–1999. Follow-up has been carried out by passive and active methods with median follow-up ranging from 3–71 months for different cancers. The proportion with histologically verified diagnosis for various cancers ranged between 52–100%; death certificate only cases (DCOs) comprised 0–34%; 54–93% of total registered cases were included for survival analysis. Complete follow-up at five years ranged from 50–85% for different cancers. Five-year age-standardized relative survival rates of common cancers were cervix (59%), lung (7%), breast (59%), thyroid (86%), oesophagus (11%), liver (2%), non-melanoma skin (75%), colon (45%) and oral cavity (33%). Five-year relative survival by age group did not reveal any pattern or trend and was fluctuating. A majority were diagnosed with regional spread of disease, and survival decreased with increasing clinical extent of disease.Songkhla registry
The Songkhla registry is located within the Faculty of Medicine, Prince of Songkhla University. Besides a hospital cancer registry at the University hospital, the data on incident cancer cases based on population-based cancer registration have been available since 1990. The registry contributed data to the quinquennial IARC publication Cancer Incidence in Five Continents for the first time in Vol VIII[1]. The cancer registration is done by active methods. Case-finding is carried out from 23 sources of registration, comprising government and private sector hospitals, provincial health and population registration offices. The network of cancer registries in Thailand also provides data to the registry. The principal sources of information on cancer cases are hospital and pathology records. The registry caters to a mixed urban and rural population of about 1.1 million with a sex ratio of 1027 females to 1000 males in 1995. The average annual age-standardized incidence rate is 100 per 100 000 among males and 83 per 100 000 among females, with a lifetime cumulative risk of one in 10 of developing cancer in the period 1993–1996. The top-ranking cancers among males are lung followed by oesophagus and oral cavity. Among females, the order is cervix, breast and thyroid.| Map. Map showing location of Songkhla, Thailand Click here to open map (PDF format) |
Data quality indices
The proportion of cases with histologically verified cancer diagnosis in this series is 88%, varying between 52% for liver cancer and 100% for many cancers. The proportion of cases registered as death certificate only (DCOs) is 2%, ranging from nil for many cancers to 34% for unspecified leukaemia. Cases excluded for having no follow-up information constitute 15%. The exclusion of cases from the survival analysis is the greatest in unspecified leukaemia (46%) and the least in cancer of the tonsil (7%). Thus, 54–93% 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, Songkhla, Thailand, 1990–1999 cases followed-up until 2003 Click here to open table (PDF format) Click here to open comparative statistics by registry |
Outcome of follow-up
Follow-up has been carried out predominantly by passive methods. These include abstraction of cancer mortality information from the vital statistics division records. The abstracted data are matched with the incident cancer database. Unmatched incident cases are then subjected to one or more of the following to obtain the vital status information: repeated scrutiny of records in the hospitals and linkage with referral system, government free health service and insurance system.The closing date of follow-up was 31st December 2003. The median follow-up ranged from 3 months for liver cancer to 71 months for thyroid cancer. Complete follow-up information at five years from the incidence date ranged from 85% for myeloid leukaemia to 50% for non-melanoma skin cancer. The losses to follow-up occurred evenly in all the time periods of <1 year, 1–3 years, 3–5 years and >5 years and are ascertained to be random.
 | Table 2. Number and proportion of cases with complete / incomplete follow-up and median follow-up (in months) by site, Songkhla, Thailand, 1990–1999 cases followed-up until 2003 Click here to open table (PDF format) Click here to open comparative statistics by registry |
Survival statistics
All ages and both sexes together
The 5-year relative survival is the highest in thyroid cancer (88%) followed by non-melanoma skin (74%). The lowest survival rate was encountered with liver cancer 2%. Lip (69%) and nasopharynx (46%), among other head and neck cancers, and colon (48%) and rectum (35%), among gastrointestinal cancers, have a higher survival than others. Survival from cancers of the urinary system is 45% for urinary bladder and 36% for kidney. Hodgkin lymphoma had a better survival (56%) than non-Hodgkin (44%). The survival figures for leukaemias are 49% for lymphoid, 15% for myeloid and 25% for unspecified.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, Songkhla, Thailand, 1990–1999 cases followed-up until 2003 Click here to open table (PDF format) Click here to open comparative statistics by registry |
 | Figure 1a. Top ten cancers (ranked by survival), Songkhla, 1990–1999 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, Songkhla, Thailand, 1990–1999 cases followed-up until 2003 Click here to open table (PDF format) Click here to open comparative statistics by registry |
Male
The top-ranking cancers in terms of 5-year relative survival are thyroid (82%), Hodgkin lymphoma (71%), lip (69%), non-melanoma skin (65%) and penis (65%). Survival probabilities from cancers of the gallbladder, pancreas, bone, Hodgkin lymphoma and multiple myeloma are noticeably higher among males than females. | Figure 1b. Top five cancers (ranked by survival), Male, Songkhla, 1990–1999 Click here to open figure (PDF format) Click here to open graph for all the cancer sites |
Female
The highest 5-year relative survival was observed in thyroid cancer (90%) followed by non-melanoma skin (82%) and corpus uteri (72%). The figures for breast, cervix and ovary are 63%, 62% and 50%, respectively. Survival was distinctly higher among females than males in most cancers of the head and neck, rectum, nose and sinuses, skin, connective tissue, kidney and brain. | Figure 1c. Top five cancers (ranked by survival), Female, Songkhla, 1990–1999 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 does not reveal any pattern or trend and is observed to be fluctuating. | Table 4b. Site-wise number of cases, 5-year absolute and relative survival by age group, Songkhla, Thailand, 1990–1999 cases followed-up until 2003 Click here to open table (PDF format) Click here to open comparative statistics by registry |
Extent of disease
Among the known categories of extent of disease for selected cancers, most cases were diagnosed with regional spread of disease at the time of diagnosis: tongue (31%), larynx (40%), breast (35%), cervix (55%) and ovary (29%). The extent of disease is unknown in a substantial proportion ranging from 17–42%. The 5-year absolute survival by extent of disease followed the expected pattern: highest for localized cases followed by regional and distant metastasis cases among known categories of extent of disease with the exception of laryngeal cancer. | Table 5. Proportion (%) of cases and 5-year absolute survival by extent of disease and site, Songkhla, Thailand, 1990–1999 Click here to open table (PDF format) Click here to open comparative statistics by registry |
 | Figure 2a-2e. Absolute survival from selected cancers by extent of disease: Songkhla, Thailand Click here to open figures (PDF format) |
 | Figure 2a. Absolute survival by extent of disease: Songkhla, Thailand: Cancer of the tongue Click here to open figure (PDF format) Click here to open comparative statistics by cancer site |
 | Figure 2b. Absolute survival by extent of disease: Songkhla, Thailand: Cancer of the larynx Click here to open figure (PDF format) Click here to open comparative statistics by cancer site |
 | Figure 2c. Absolute survival by extent of disease: Songkhla, Thailand: Cancer of the breast Click here to open figure (PDF format) Click here to open comparative statistics by cancer site |
 | Figure 2d. Absolute survival by extent of disease: Songkhla, Thailand: Cancer of the cervix Click here to open figure (PDF format) Click here to open comparative statistics by cancer site |
 | Figure 2e. Absolute survival by extent of disease: Songkhla, Thailand: Cancer of the ovary Click here to open figure (PDF format) Click here to open comparative statistics by cancer site |
References
- 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)