open this chapter (vol 2, 2011) in PDF format

Karachi cancer registry

The Karachi cancer registry was the first population-based cancer registry in Pakistan. It was established in 1995 at the Sindh Government Services Hospital by the government of Sindh, and contributed data to the quinquennial IARC publication Cancer Incidence in Five Continents for the first time in Vol VIII^[1]. cancer registration is done by active methods^[2]. Over 50 sources of registration, comprising hospitals in the government and private sectors and pathology laboratories, are visited for data collection on incident cancer cases from the medical records. The registry caters to a population of about 1.7 million in 1996 with a sex ratio of 856 females to 1000 males. The average annual age-standardized incidence rate is 139 per 100 000 among males and 169 per 100 000 among females with a lifetime cumulative risk of one in 6 of developing cancer for both sexes in the period 1995–1997^[2]. The top-ranking cancers among males are lung followed by oral cavity and larynx. Among females, the order is breast, ovary and oral cavity.

Map. Map showing location of South-Karachi, Pakistan Click here to open map (PDF format)

The registry has contributed data on survival from selected cancers of the head and neck registered during 1995–1999 for the first time in this volume of the 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 varied between 98–100%. No cases were registered on the basis of a death certificate only. The exclusion of cases owing to the non-availability of any follow-up information is 7%, ranging from 9% in cancer of the tonsil to 7% for oral cavity. Thus, 86–93% 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, South Karachi, Pakistan, 1995–1999 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 was carried out predominantly by active methods. These included abstraction of cancer mortality information from death certificates. The abstracted data are matched with the incident cancer database. Unmatched incident cases are then subjected to repeated scrutiny of records in the respective sources of registration and postal/telephone enquiries to obtain the vital status information.

The closing date of follow-up was 31^st December 2003. The median follow-up ranged from 29 months for cancer of the oral cavity to 36 months in tongue cancer. Complete follow-up information at five years from the incidence date ranged between 67–76%. The losses to follow-up are spread over all the time intervals from incidence date, from <1 year to >5 years. This minimizes the bias of estimation of survival probability in the respective years from the incidence date.

Table 2. Number and proportion of cases with complete / incomplete follow-up and median follow-up (in months) by site, South Karachi, Pakistan, 1995–1999 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 for cancer of the salivary gland (46%), followed in order by oral cavity (38%), tongue (37%) and tonsil (31%).

The 5-year age-standardized relative survival (ASRS) probability for all ages together was greater than the corresponding unadjusted one in cancers of the tongue, oral cavity and tonsil; this was reversed for cancer of the salivary gland. The 5-year ASRS (0–74 years of age) is less than the corresponding ASRS (all ages) for most cancers.

Table 3. Comparison of 1-, 3- and 5-year absolute and relative survival and 5-year age-standardized relative survival (ASRS) by site, South Karachi, Pakistan, 1995–1999 cases followed-up until 2003 Click here to open table (PDF format) Click here to open comparative statistics by registry

Sex

Table 4a. Site-wise number of cases, 5-year absolute and relative survival by sex, South Karachi, Pakistan, 1995–1999 cases followed-up until 2003 Click here to open table (PDF format) Click here to open comparative statistics by registry

Male

The 5-year relative survival was the highest for cancer of the salivary gland (45%), and the lowest was tongue cancer (25%). Survival from cancers of the oral cavity and tonsil is noticeably higher among males than females.

Female

The top ranking cancer on 5-year relative survival was the tongue (52%), and the lowest in the ranking was tonsil (16%). Survival was markedly higher among females than males in cancer of the tongue.

Age group

The 5-year relative survival by age group did not display any pattern or trend and was observed to fluctuate with increasing age groups.

Table 4b. Site-wise number of cases, 5-year absolute and relative survival by age group, South Karachi, Pakistan, 1995–1999 cases followed-up until 2003 Click here to open table (PDF format) Click here to open comparative statistics by registry

Extent of disease

A majority of cases have been diagnosed with a regional spread of disease: tongue (51%), oral cavity (53%), salivary gland (46%) and tonsil (79%). Cases diagnosed with distant metastasis were negligible. Localized stage cancers are the least common among cancer of the tonsil (13%), while in the rest it ranged between 33–38%. The extent of disease was unknown in 8–22%. 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.

	Table 5. Proportion (%) of cases and 5-year absolute survival by extent of disease and site, South Karachi, Pakistan, 1995–1999 Click here to open table (PDF format) Click here to open comparative statistics by registry
	Figure 1a-1d. Absolute survival from selected cancers by extent of disease: South Karachi, Pakistan open the figures in PDF format
	Figure 1a. Absolute survival by extent of disease: South Karachi, Pakistan: Cancer of the tongue Click here to open figure (PDF format) Click here to open comparative statistics by cancer site
	Figure 1b. Absolute survival by extent of disease: South Karachi, Pakistan: Cancer of the oral cavity Click here to open figure (PDF format) Click here to open comparative statistics by cancer site
	Figure 1c. Absolute survival by extent of disease: South Karachi, Pakistan: Cancer of the salivary gland Click here to open figure (PDF format) Click here to open comparative statistics by cancer site
	Figure 1d. Absolute survival by extent of disease: South Karachi, Pakistan: Cancer of the tonsil Click here to open figure (PDF format) Click here to open comparative statistics by cancer site

---

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. Bhurgri Y, Bhurgri A, Hassan SH, Zaidi SH, Rahim A, Sankaranarayanan R and Parkin DM. Cancer incidence in Karachi, Pakistan: first results from Karachi Cancer Registry. Int J Cancer. 2000; 85(3): 325-9.
   (link to pubmed)