Height and cancer incidence in the Million Women Study: prospective cohort, and meta-analysis of prospective studies of height and total cancer risk

Abstract

Background: Epidemiological studies have shown that taller people are at increased risk of cancer, but it is unclear if height-associated risks vary by cancer site, or by other factors such as smoking and socioeconomic status. Our aim was to investigate these associations in a large UK prospective cohort with sufficient information on incident cancer to allow direct comparison of height-associated risk across cancer sites and in relation to major potential confounding and modifying factors.

Methods: Information on height and other factors relevant for cancer was obtained in 1996-2001 for middle-aged women without previous cancer who were followed up for cancer incidence. We used Cox regression models to calculate adjusted relative risks (RRs) per 10 cm increase in measured height for total incident cancer and for 17 specific cancer sites, taking attained age as the underlying time variable. We also did a meta-analysis of published results from prospective studies of total cancer risk in relation to height.

Findings: 1 297 124 women included in our analysis were followed up for a total of 11·7 million person-years (median 9·4 years per woman, IQR 8·4-10·2), during which time 97 376 incident cancers occurred. The RR for total cancer was of 1·16 (95% CI 1·14-1·17; p<0·0001) for every 10 cm increase in height. Risk increased for 15 of the 17 cancer sites we assessed, and was statistically significant for ten sites: colon (RR per 10 cm increase in height 1·25, 95% CI 1·19-1·30), rectum (1·14, 1·07-1·22), malignant melanoma (1·32, 1·24-1·40), breast (1·17, 1·15-1·19), endometrium (1·19, 1·13-1·24), ovary (1·17, 1·11-1·23), kidney (1·29, 1·19-1·41), CNS (1·20, 1·12-1·29), non-Hodgkin lymphoma (1·21, 1·14-1·29), and leukaemia (1·26, 1·15-1·38). The increase in total cancer RR per 10 cm increase in height did not vary significantly by socioeconomic status or by ten other personal characteristics we assessed, but was significantly lower in current than in never smokers (p<0·0001). In current smokers, smoking-related cancers were not as strongly related to height as were other cancers (RR per 10 cm increase in height 1·05, 95% CI 1·01-1·09, and 1·17, 1·13-1·22, respectively; p=0·0004). In a meta-analysis of our study and ten other prospective studies, height-associated RRs for total cancer showed little variation across Europe, North America, Australasia, and Asia.

Interpretation: Cancer incidence increases with increasing adult height for most cancer sites. The relation between height and total cancer RR is similar in different populations.

Funding: Cancer Research UK and the UK Medical Research Council.

Figure 1

Relative risks (RRs) and 95% floated CIs (FCIs) for total incident cancer, by height RRs are adjusted for age, region, socioeconomic status, smoking, alcohol intake, body-mass index, strenuous exercise, age at menarche, parity, and age at first birth, and are plotted against the mean measured height in each category.

Figure 2

Relative risks (RRs) and 99% CIs per 10 cm increase in height for incident cancer at 17 specific sites and for total cancer The doted line represents the RR per 10 cm increase in height for total cancer. *RRs are adjusted for age, region, socioeconomic status, smoking, alcohol intake, body-mass index, strenuous exercise, age at menarche, parity, and age at first birth.

Figure 3

Relative risks (RRs) and 99% CIs per 10 cm increase in height for all incident cancer, by various characteristics at recruitment The dotted line represents the RR per 10 cm increase in height for all women. *Standardised to the distribution of self-reported heights within each subgroup of the whole study population. †RRs are adjusted as appropriate for age, region, socioeconomic status, smoking, alcohol intake, body-mass index, strenuous exercise, age at menarche, parity, and age at first birth.

Figure 4

Relative risks (RRs) and 95% floated CIs (FCIs) for all incident cancer in relation to height, and by socioeconomic status The baseline category (RR=1·0) is women shorter than 160 cm from the highest socioeconomic group. RRs are adjusted for age, region, smoking, alcohol intake, body-mass index, strenuous exercise, age at menarche, parity, and age at first birth. RRs are plotted against the mean measured height in each category of height (<160 cm, 160–165 cm, 165–170 cm, ≥170 cm), within categories of socioeconomic status.

Figure 5

Relative risks (RRs) and 99% CIs per 10 cm increase in height, for all incident cancer and for incident cancer at 17 specific sites, in never and current smokers Dotted lines represent the RR for total cancer. *RRs are adjusted for age, region, socioeconomic status, alcohol intake, body-mass index, strenuous exercise, age at menarche, parity, and age at first birth.

Figure 6

Relative risks (RRs) and 95% CIs per 10 cm increase in height for incident smoking-related and other specified cancers, in never and in current smokers *RRs are adjusted for age, region, socioeconomic status, alcohol intake, body-mass index, strenuous exercise, age at menarche, parity, and age at first birth.

Figure 7

Meta-analysis of results from prospective studies: study-specific and summary relative risks (RRs) and 95% CIs for all cancer per 10 cm increase in height The dotted lines represent the summary RRs. NA=not available. *Mean years of birth estimated as necessary. †Includes 24% (men) and 2% (women) pipe or cigar smokers. ‡Category midpoints used to estimate mean heights in height categories. §Method of Chêne and Thompson used to estimate mean heights in height categories.