Cancer Statistics - Karmanos Cancer Institute

Differences in Completeness of Follow-up
in a Population-Based Cancer Registry
George W. Dombi, Cecilia Yee, Richard K. Severson, Jeannette Korczak and Ikuko Kato (Principal Investigator)
Population-based cancer registries play a pivotal role in providing
unbiased information on the occurrence of cancer arising in a
defined population 1 . This information is crucial to monitor emerging
patterns of cancer incidence, prevalence and survival. In the
US, the Surveillance, Epidemiology and End Results (SEER) data
have revealed differences in cancer incidence and survival between
Caucasians and African Americans 2 . The most commonly diagnosed
cancers in US women and men are breast and prostate cancers,
respectively, and racial disparities in the 5-year relative survival for
these two types of cancer have long been recognized 3, 4 . Validity of
these comparisons depends on the assumption that completeness
of follow-up is not only highly satisfactory, but also comparable between
races. Because cases lost to follow-up may not be representative
samples of the whole patient population, any racial differences
in follow-up could potentially introduce bias into the observed
racial disparities in cancer survival. Thus, we conducted a study to:
(i) identify characteristics of breast cancer and prostate cancer patients
who are lost to follow-up and (ii) assess whether there is any
differential follow-up between African Americans and Caucasians,
after adjustment for other factors related to loss to follow-up.
Test set included 36,925 female breast cancer patients and 40,943
prostate cancer patients, either Caucasian or African Americans,
who were diagnosed between 1992 and 2002 and at age greater
than 20 years were included in the study. During the average 6.6
years of follow-up, 2.4% of the breast cancer patients and 1.4% of
the prostate cancer patients were lost. Losses to follow-up occurred
more frequently in Caucasians than African Americans, particularly
for breast cancer. Unknown social security number (SSN) was
the strongest predictor. Patients younger than 65 years, married
women and men with unknown marital status were more likely to
be lost. Local tumor stage and non-hospital reporting source were
associated with higher risk of loss to follow-up in the logistic regression,
but not in the time-dependent Cox proportional model. While
a history of multiple primary cancers appeared to reduce the risk of
loss to follow-up, no surgery or no radiation treatment records were
associated with an increased risk of follow-up loss for either cancer.
These observations are contrary to our working hypothesis that
African Americans, as well as patients with lower socio-economical
status, may be more likely to be lost to follow-up. The causes for
the unexpected lower rate of African Americans lost to follow-up
remains to be elucidated. It is not surprising that an advanced stage
of disease showed a strong inverse association with loss to followup
because all deceased cases were considered to be completely
followed. Major determinants of loss to follow-up were concerned
with incomplete patient information. According to the results of
this study, it is highly recommended that complete and accurate
personal identifying information be obtained; otherwise additional
information concerning potential contacts of the patients would be
helpful. Aside from that, results from the logistic regression analyses
may prove to be especially useful in planning targeted follow-up
to identify those patients who are likely to be lost following the
initial diagnosis and treatment period.
23
100 MDCSS (1992 – 2002) Breast Cancer Patients Lost to Follow-up
100 MDCSS (1992 - 2002) Prostate Cancer Patients Lost to Follow-up
80
Caucasian
African American
1.7%
2.6%
80
Caucasian
African American
1.5%
1.0%
PERCENTAGE
=65 years old
40 Not married
1.0%
1.5%
4.3%
PERCENTAGE
1.1%
1.0%
2.9%
Married
3.1%
3.8%
1.1%
20 Unknown
=65 years old
40 Not married
Married
20 Unknown
4.3%
SSN known
SSN unknown 1975 1980
2.1% 39.7%
SSN known 0.9% 51.5%
SSN unknown 1975 1980
0% 1% 2% 3% 4% 5% …
Lost to Follow-up
37% 38% 39% 40% 0% 1% 2% 3% 4% 5% … 49% 50% 51% 52%
Lost to Follow-up
References:
1. Parkin DM. The evolution of the population-based cancer registry.
Nat Rev Cancer. 2006;6:603-12.
2. Ries LAG, Harkins D, Krapcho M, et al (eds). SEER Cancer Statistics Review,
1975-2003, National Cancer Institute. Bethesda, MD, http://seer.cancer.gov/
csr/1975_2003/,based on November 2005 SEER data submission, posted to
the SEER web site, 2006.
3. Young JL Jr, Ries LG, Pollack ES. Cancer patient survival among ethnic groups
in the United States. J Natl Cancer Inst 1984 ;73:341-352.
4. Clegg LX, Li FP, Hankey BF, Chu K, Edwards BK. Cancer survival among US whites
and minorities: a SEER (Surveillance, Epidemiology, and End Results) Program
population-based study. Arch Intern Med. 2002 Sep 23;162(17):1985-93.