Critical appraisal:Hartman M, Liu J, Czene K, Miao H, Chia KS, Salim A, et al 2013

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Critical Appraisal

Article being appraised

Hartman M, Liu J, Czene K, Miao H, Chia KS, Salim A, et al. Birth rates among female cancer survivors: a population-based cohort study in Sweden. Cancer 2013 May 15;119(10):1892-9 Available from: http://www.ncbi.nlm.nih.gov/pubmed/23436251.


Applicable clinical question

Key Facts

Study Design

cohort study

Study aims:

To evaluate trends in birth rates among female cancer survivors, and factors affecting these rates

Number of Patients:

3907708

From 3,907,708 Swedish women, selected 16-45 year olds born >1931 + alive in 1960 -> ascertained number and dates of live childbirths + date of cancer Dx (if present), and followed them until death, emigration, or end of followup (December 31, 2002).

-Cancer group: 42,691 women <45 years with a history of cancer were identified from the Swedish Multi-Generation Register
and the Swedish Cancer Register.
-Compared with the background population - 3,011,113 cancer-free women were matched to the female cancer survivors according to attained age and year of birth, and number of live childbirths

Over the study period (43 years) 5060 participants (0.1%) were lost to f/up and 848,844 (21.7%) were excluded because they were out of the observed age range of 16-45 years.
Reported outcome(s):

relative birth rates (standardized birth ratios (SBRs))

Results of outcome(s):

-Of cancer survivors, 4932 (11.6%) gave birth to 8080 children, 1 year or more after cancer whereas 1,864,511 of the background population (61.9%) gave birth to 3,786,420 children over the same calendar period and attained age
-cancer survivors were 27% less likely to give birth than the general population (SBR=0.73, 95%CI=0.72-0.75) - proportion did not change over time
-Cancers with practically similar relative birth rates as the background population: thyroid (SBR=0.98, 95%CI=0.93-1.03), head and neck (SBR=1.00, 95%CI=0.87-1.14), thoracic (SBR=1.01, 95%CI=0.76-1.31), and melanoma (SBR=1.04, 95%CI=0.99-1.10)
-Cancer significantly less likely to give birth than the background population: reproductive organs (minus ovary, SBR=0.32, 95%CI=0.29-0.35), breast (SBR=0.52, 95%CI=0.47-0.57), and ovary (SBR=0.56, 95%CI=0.51-0.61).
-In childhood cancer: Dx <1980 (SBR=0.76, 95%CI=0.70-0.81) had higher SBRs than those Dx >1980 (SBR=0.57, 95%CI=0.47-0.67)
-Adolescent cancers (SBR=0.83, 95%CI=0.79-0.88) had higher SBRs than survivors of childhood (SBR=0.72, 95%CI=0.67-0.77) and adult cancer (SBR=0.72, 95%CI=0.70-0.74)
-Low SBRs in women who were recently diagnosed and women older than 36 years
-parous at diagnosis had a lower SBR (0.50, 95%CI=0.48-0.53) than nulliparous (SBR=0.87, 95%CI=0.85-0.90) - for all cancers
-relative risk of twinning was not larger than that of the background population, neither in the 1980s
(SBR=0.82, 95% CI=0.54-1.17) nor in the 1990s (SBR=0.92, 95% CI=0.73-1.13).
-With increasing age, survivors of adult cancer became less likely to give birth compared with women ofsimilar age in the background population
-Survivors of childhood and adolescent cancer showed a steep increase in relative fertility after the age of 35 years.
-Multivariate analyses: cancer site (reproductive organs), age at onset of cancer (<12 years), and parity status were all significant and independent predictors of a reduced probability of giving birth after diagnosis.

Comments on results:

-excluded births occurring within 12 months after diagnosis (i.e. included women who conceived at least 3 months after Dx).
-Missing data was equally likely in both groups, so chose to use standardized birth ratio to handle the nondifferential bias
-of 3,907,708 Swedish women, 42,691 (1.1%) were diagnosed with cancer before the age 45: age at diagnosis for female cancer survivors had a median of 36 years and a range of 0 to 44 years over a median follow-up of 4.5 years.
-most were Dx with cancer during adulthood (92.7%), breast (n=12,139), reproductive organs (n=6493), and melanoma skin (n=4637).


Evidence ratings

Level of evidence

III-3

Risk of bias
High risk of bias Comments: Population registry study
Result of appraisal

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Completed by

Dr Michelle Peate

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Article
Hartman M, Liu J, Czene K, Miao H, Chia KS, Salim A, et al. Birth rates among female cancer survivors: a population-based cohort study in Sweden. Cancer 2013 May 15;119(10):1892-9 Available from: http://www.ncbi.nlm.nih.gov/pubmed/23436251.
Assigned to
User:Michelle.peate
Topic area
Guidelines:COSA:Cancer fertility preservation guidelines/Impact of cancer on fertility
Clinical question
Form
Form:Critical appraisal


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