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Maine Center for Disease Control & Prevention

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Maine Cancer Registry - Technical Notes

Reportable Cancers and Site Definitions

Not all cancers diagnosed in Maine are reported to the MCR. Cancers that are reported include all malignant cancers that are in situ or invasive with the exception of basal and squamous cell carcinoma of the skin. The MCR also collects data concerning benign tumors of the brain. Site definitions for annual reports are consistent with those used by the National Institute of Health's Surveillance, Epidemiology and End Results (SEER) Program for calculating rates. Therefore, annual reports exclude all in situ cancers, with the exception of in situ bladder cancer. For a complete listing of site and histology codes used for calculating rates. See ICD-O Codes.

Age-adjusted Rates

Why age adjust?

Different communities have different age structures. The age structure of a community determines what kind of health problems will be more common. A community made up of more families with young children will have more bicycle accidents than a community with more individuals who are older. Likewise, a community with more individuals who are older will have more chronic disease, including cancer. Age adjustment allows rates of disease to be compared between different communities with different age structures.

How is age-adjustment done?

Age adjustment is done using a statistical procedure called the direct method. The steps for age-adjustment are:

  1. The number of cases and population of new cancer cases are divided into 5-year age grouping (i.e. 0-4, 5-9, 10-14 …80-84, 85+).
  2. Incidence rates are calculated for each age group (called age-specific rates) by dividing the number of cases in an age group by the population in that age group.
  3. A standard population is chosen (we used the 2000 United States Standard population). The proportion of the standard population is determined for each age group. This is the weight.
  4. The age-specific rate is multiplied by the weight of the respective age group, making a weighted rate.
  5. The weighted rates are added together, giving the age-adjusted rate.

Here's an example of Age-adjusted rates using all cancers reported in Maine that were diagnosed in 2003:

Age Group Number of New Cancer Cases (a) Population in Maine (b) Rates per 100,000 c = ((a/b) x 100,000) 2000 Standard Weights (d) Weighted Rate (c x d)
0 - 4 yrs. 15 67374 22.3 0.069 1.5
5 - 9 yrs. 8 73921 10.8 0.073 0.8
10 - 14 yrs. 16 88292 18.1 0.073 1.3
15 - 19 yrs. 25 93546 26.7 0.072 1.9
20 - 24 yrs. 44 83566 52.7 0.066 3.5
25 -29 yrs. 39 66031 59.1 0.065 3.8
30 - 34 yrs. 82 80369 102.0 0.071 7.2
35 - 39 yrs. 138 96183 143.5 0.081 11.6
40 - 44 yrs. 246 111546 220.5 0.082 18.1
45 - 49 yrs. 384 110625 347.1 0.072 25.0
50 - 54 yrs. 560 100500 557.2 0.063 34.9
55 - 59 yrs. 729 83407 874.0 0.048 42.4
60 - 64 yrs. 818 62680 1305.0 0.039 50.6
65 - 69 yrs. 934 49390 1891.1 0.034 64.8
70 -74 yrs. 1056 45518 2320.0 0.032 73.7
75 - 79 yrs. 1015 40258 2521.2 0.027 68.1
80 - 84 yrs. 759 27863 2724.0 0.018 48.6
85+ yrs. 521 24659 2112.8 0.016 32.8
Total 7389 1305728 565.9 1.000 490.7

In the above example, the rate before age adjustment (the crude rate) is 565.9 per 100,000 people and the age adjusted rate is 490.7 per 100,000 people.

A Few Words about County Rates

The number of new cancers in a county varies from year to year. Cancer rates therefore also vary from year to year. With a smaller number of cases, there is more variation from year to year. Here is an example of random variation in the number of cases: One county might have 4 cases of brain cancer one year, 9 cases the next year, no cases the next year, 8 the next and 3 the next year. Over the five years there is an average of 5 cases a year. In general, when there are less than 30 cases a year it can be difficult to distinguish between such normal variation in the number of cases and meaningful changes in the cancer rates. The small population of Maine counties mean caution must be used when presenting rates of cancer in some counties. To avoid presenting unstable numbers (with lots of variation), this report presents county-level data for the four most common cancer sites - lung, breast (female only), prostate and colon-rectum, as well as all cancers combined.

U.S. SEER Rates

What is SEER?

The National Cancer Institute funds the Surveillance, Epidemiology and End Results (SEER) cancer registries. SEER collects information on cancers from a statistical sample of the United States population composed of 17 population-based registries. These registries represent approximately 26 percent of the US population. The sample is designed to be fairly representative of the U.S. population. Because the non-white population of Maine is less than 2%, the SEER rates for Whites only are used for all comparisons in annual reports.

Why is caution needed in interpreting comparisons using an all-white population?

Rates of cancer vary by race. These differences are due to cultural differences in personal habits, dietary practices, and environmental exposures that may change the risk of cancer in a population. In addition, many ethnic and racial minorities are at a disadvantage relative to access and availability of health care, preventative services and health education in part due to language differences as well as low income and education. Thus minorities may experience increased cancer incidence and mortality. In the U.S., people of white race have a higher risk of female breast cancer, melanoma and bladder cancer than persons of other races. Whites have a lower risk compared to other races for prostate, colorectal and cervical cancer. Because the non-white population of Maine is relatively small, in the future we will need to combine a number of years of data to be able to reliably report rates in these groups.

Changes in Case-Finding Starting in 1995

Beginning in 1995, physicians, non-hospital facilities, and pathology labs were added to the list of reporting sources for the registry. In that year, the Maine Cancer Registry also began performing Death Clearance, in which death certificates are reviewed to identify missing cases.

ICD-O-3 Codes for Oral Cavity & Pharynx

Site Category
Oral Cavity & Pharynx
ICD-O-3 Site Codes
Lip C000-C009
Tongue C019-C029
Major Salivary Gland C079-C089
Floor of Mouth C040-C049
Gum & Other Mouth C030-C039, C050-C059, and C060-069
Nasopharynx C110-C119
Tonsil C090-C099
Oropharynx C100-C109
Hypopharynx C129, C130-C139
Pharynx C140 and C142-C148

Note: Oral Cavity & Pharynx codes exclude histologies 9590-9989.

ICD-O-3 Codes for Digestive System

Site Category
Digestive System
ICD-O-3 Site Codes
Esophagus C150-C159
Stomach C160-C169
Small Intestine C170-C179
Colon C180-C189 and C260
Rectum & Rectosigmoid C199-C209
Anus & Anocanal C210-C212 and C218
Liver C220
Intrahepatic Bile Duct C221
Gallbladder C239
Other Biliary C240-C249
Pancreas C250-C259
Retroperitoneum C480
Peritoneum C481-C482
Other Digestive Organs C268-C269 and C488

Note: Digestive System codes exclude histologies 9590-9989.

ICD-O-3 Codes for Respiratory System

Site Category
Respiratory System
ICD-O-3 Site Codes
Nasal Cavity & Sinuses C300-C301, and C310-C319
Larynx C320-C329
Lung & Bronchus C340-C349
Pleura C384
Trachea, Mediaspinum, & Other Respiratory Organs C339 and C381-C383, C388, C390-399

Note: Respiratory System codes exclude histologies 9590-9989.

ICD-O-3 Codes for Bones & Joints

Site Category ICD-O-3 Site Codes
Bones and Joints C400-C419

Note: Bones & Joints codes exclude histologies 9590-9989.

ICD-O-3 Codes for Soft Tissue

Site Category ICD-O-3 Site Codes
Soft Tissue (including Heart) C380, C470-C479, C490-C499

Note: Soft Tissue codes exclude histologies 9590-9989.

ICD-O-3 Codes for Melanoma of Skin

Site Category ICD-O-3 Site Codes
Melanoma of Skin C440-C449

Note: Melanoma codes include histologies 8720-8790 only.

ICD-O-3 Codes for Breast

Site Category ICD-0-3 Site Codes
Breast C500-C509

Note: Breast codes exclude histologies 9590-9989.

ICD-O-3 Codes for Eye

Site Category ICD-O-3 Site Codes
Eye C690-C699

Note: Eye codes exclude histologies 9590-9989.

ICD-O-3 Codes for Female Genital System

Site Category
Female Genital System
ICD-O-3 Site Codes
Cervix C530-C539
Uterus C540-C559
Ovary C569
Vagina C529
Vulva C510-C519
Other Female Genital Organs C570-C589

Note: Female Genital System codes exclude histologies 9590-9989.

ICD-O-3 Codes for Male Genital System

Site Category
Male Genital System
ICD-O-3 Site Codes
Prostate C619
Testis C620-C629
Penis C600-C609
Other Male Organs C680-C689

Note: Male Genital System codes exclude histologies 9590-9989.

ICD-O-3 Codes for Urinary System

Site Category
Urinary System
ICD-O-3 Site Codes
Bladder C670-C679
Kidney & Renal Pelvis C649-C659
Ureter C669
Other Urinary Organs C680-C689

Note: Urinary System codes exclude histologies 9590-9989.

ICD-O-3 Codes for Brain & Other Nervous System

Site Category
Brain & Other Nervous System
ICD-O-3 Site Codes
Brain C710-C719 (excluding meningioma)
Other Nervous System C710-C719 (meningioma only), C700-C709, C720-C729

Note: Brain & Other Nervous System codes exclude histologies 9590-9989.

ICD-O-3 Codes for Endocrine System

Site Category
Endocrine System
ICD-O-3 Site Codes
Thyroid C739
Other Endocrine C379, C740-C759

Note: Endocrine System codes exclude histologies 9590-9989.

ICD-O-3 Codes for Lymphomas

Site Category
Lymphomas
ICD-O-3 Histology Codes
Hodgkins Disease Includes histologies 9650-9667 only
Non-Hodgkin Lymphoma Includes histologies 9590-9595 and 9670-9719 only

ICD-O-3 Codes for Multiple Myeloma

Site Category ICD-O-3 Histology Codes
Multiple Myeloma Includes histologies 9731-9732 only

ICD-O-3 Codes for Leukemias

Site Category
Leukemias
ICD-O-3 Histology Codes
All Leukemias 9800-9948, 9963, 9964 only