Science - USA (2020-01-03)

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cancer genomics and molecular biology.
Pan-African initiatives, such as the Human
Heredity and Health in Africa (H3Africa) ini-
tiative, have developed common protocols,
data systems, and collaborative networks
that are developing the infrastructure and
resources required to address cancer needs
in SSA. Africa-based organizations that foster
cancer research, translation, infrastructure,
and training also exist, including the African
Academy of Sciences and the African Organi-
zation for Research and Training in Cancer.
The World Economic Forum has initiated a

“Leapfrogging with Precision Medicine” ini-
tiative that will advance the use of genetics
and genomics in cancer prevention and treat-
ment. These and many other institutions and
activities have the potential to develop the
knowledge and sustainable resources needed
to address the cancer burden in SSA.
In addition to benefiting the treatment of
cancer patients in SSA, the knowledge gained
from research on the continent will be inform-
ative for cancer globally. Evidence suggests
that diversity in study populations will im-
prove the ability to generate and generalize
knowledge that can be applied to cancer and
other diseases. For example, rare mutations
judged to be pathogenic on the basis of Cau-
casian mutation frequency data were later
found to occur commonly in African Ameri-
can populations ( 10 ). Knowledge of mutation
frequency subsequently led to the opposite
conclusion that these variants were non-
pathogenic. This misclassification of patho-
genicity led to molecular misdiagnoses that
could have been avoided had diverse popula-

tions been included in the original study co-

hort. Similarly, it has been observed that use

of artificial intelligence and other “big data”

approaches in diagnostic and therapeutic

applications will be suboptimal if these ap-

proaches are trained and validated in nondi-

verse populations.

A limited scope of population data may

perpetuate or exacerbate existing biases in

the information needed to generate effec-

tive clinical and public health interventions

( 11 ). Thus, it is not only the underrepresented

population that will benefit from increased

research representation but all populations.

There is growing evidence that genetic risk

prediction models developed in Cauca-

sian populations may not be appropriate in

African-descent populations. These results

suggest that ancestry-specific models may

be required to optimally predict cancer

risk. Such models may use genetic variants

defined from the discovery of relevant race-

specific disease-associated variants and/or

use ancestry-specific genomic markers to de-

fine ancestry rather than self-identified race

or ethnicity.

Because of the underlying genetic and ge-

nomic relationships between Africans and

members of the African diaspora (primarily

in North America and Europe), knowledge

gained from research in SSA can be used to

address health disparities that are prevalent

in members of the African diaspora. West

African genomic ancestry (the ancestral ori-

gin of most African Americans) has been re-

ported to confer the highest genomic risk for

prostate cancer of any population worldwide

( 12 ). Selection against a prostate cancer sus-

ceptibility locus on chromosome 2q37 has led

to lower frequencies of this risk allele in Cau-

casians and higher frequencies in Africans

and African Americans ( 12 ). KhoeSan (an in-

digenous southern African people) ethnicity

has also been associated with prostate cancer

risk ( 13 ). These data from African popula-

tions may help elucidate the causes of cancer

disparities, particularly in African Americans.

Diagnostic, monitoring, and treatment

technologies developed out of necessity in

low-resource settings provide an opportunity

for cost-efficient and accessible

technologies that can be imple-

mented in HICs. In particular,

development of point-of-care

technologies that provide rapid

and accurate cancer diagnosis

or treatment in SSA could be ap-

plied in community settings to

address disparities in access to

cancer services in HICs. When

technologies, including data-

derived models of risk or prog-

nosis, are not developed so that

they can be applied in diverse

settings and populations, health

disparities can be created or

increased ( 14 ). Development of

technologies that can be used

in SSA could provide knowledge

about optimal implementation

of these technologies world-

wide. Advances in science and

technology and the concomitant

increase in capacity for health

improvements will increase di-

versity as a means to remove

bias from cancer genomics stud-

ies and improve the quality of cancer pre-

vention and treatment globally. j

REFERENCES AND NOTES

1. D. Parkin et al., Eds., Cancer in Sub-Saharan Africa (IARC
   Scientific Publication no. 167, IARC, 2018).


2. D. Burkitt, Br. J. Surg. 46 , 218 (1958).


3. L. Chinula et al., Curr. Opin. HIV AIDS 12 , 89 (2017).


4. J. J. Pitt et al., Nat. Commun. 9 , 4181 (2018).


5. Population Division, United Nations Department of
   Economic and Social Affairs, 2019 Revision of World
   Population Prospects; https://population.un.org/wpp.


6. V. A. McCormack et al., Breast Cancer Res. 15 , R84
   (2013).


7. Y. Zheng et al., J. Clin. Oncol. 36 , 2820 (2018).


8. T. R. Rebbeck et al., Hum. Mutat. 39 , 593 (2018).


9. C. Andrews et al., J. Glob. Oncol. 4 , 1 (2018).


10. A. K. Manrai et al., N. Engl. J. Med. 375 , 655 (2016).


11. G. Kuhnen, A. Rebhan (2019); http://www.advisory.com/
    daily-briefing/2019/02/04/ai.


12. J. Lachance et al., Cancer Res. 78 , 2432 (2018).


13. D. C. Petersen et al., BMC Med. Genomics 12 , 82 (2019).


14. D. Weiss et al., PLOS ONE 13 , e0195447 (2018).


15. The Global Cancer Observatory; https://gco.iarc.fr.

ACKNOWLEDGMENTS

The author is supported by National Institutes of Health grant

U01-CA184734.

10.1126/science.aay4743

Cervix

Ovary

23.3%

2.1%

3.4%

2.7%

Esophagus

Prostate

2.3%

0.6%

1.8%

4.2%

21.5%

18.9%

Uterus

Pancreas

2.1%

5.2%

1.1%

1.8%

2.8%

3.2%

Breast

Non-Hodgkin's

lymphoma

24.5%

25.8%

3.2%

3.1%

5.6%

3.1%

34.2%1.2%

2.1%

2.9%

6.0%

1.6%

9.5%

12.0%

4.6%

Bladder

Lung

Male HICs

Male SSA

Female HICs

Female SSA

Male HICs

Male SSA

Female HICs

Female SSA

Thyroid

Liver

1.5%

2.9%

7. 2 %

0.9%

1.2%

4.7%

1.9%

2.8%

Kaposi’s

sarcoma

Stomach

2.4%

6.2%

0.1%

2.9%

2.4%

4.5%

4.1%

<0.1%

GRAPHIC: X. LIU/

SCIENCE

INSIGHTS | PERSPECTIVES

Cancer in Africa compared with high-income countries
The occurrence of the common types of cancer in sub-Saharan Africa (SSA) differs from that in high-income countries (HICs). The
newly diagnosed cancer cases in 2018, as a percentage of the total population, are shown for SSA versus HICs. It is estimated that
incidence of the most common cancers will approximately double between 2018 and 2040 in SSA. Data were obtained from ( 15 ).

28 3 JANUARY 2020 • VOL 367 ISSUE 6473

Published by AAAS