Childhood body size affects future breast cancer risk
MedWire News: Girls with a large body type at age 7 years have a decreased risk for postmenopausal breast cancer compared with girls who who were leaner in childhood, independent of other breast cancer risk factors, study findings indicate.
Size at age 7 years also determined tumor characteristics, in particular, estrogen receptor status, report Jingmei Li (Karolinska Institutet, Stockholm, Sweden) and colleagues in the open access journal Breast Cancer Research.
Li and team studied the relationships between childhood body size and tumor characteristics in a group of 2818 breast cancer patients and 3111 controls. They asked study participants to assess their own body type at present and how they remembered themselves at 7 years old using nine pictograms of somatotypes ranging from very skinny (S1) to very fat (S9). These selections were then used to group the participants as lean (S1 to S2), medium (S3 to S4) and large (S5 to S9).
The researchers report that a large somatotype at age 7 years was associated with 27% decreased risk for postmenopausal breast cancer compared with the lean somatotype. “Although strongly associated with other risk factors such as age of menarche, adult body mass index and mammographic density, somatotype at age 7 remained a significant protective factor after adjustment [for these factors],” they say.
The significant protective effect of large body size was observed within all tumor subgroups defined by estrogen receptor (ER) and progesterone receptor status but was stronger for ER-negative tumors, where a 60% reduced risk for postmenopausal breast cancer was observed. This compared with a 20% reduced risk for ER-positive tumors.
Of note, somatotype at age 7 years was not associated with tumor size, histology, grade, or the presence or absence of metastatic nodes.
Li et al conclude that their findings may have important implications. “Given the strength of the associations, and the ease of retrieval of information on childhood shape from old photographs, childhood body size is potentially useful for building breast cancer risk or prognosis models”.
However, they add: “There remain unanswered questions on mechanisms driving this protective effect.”
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By Laura Dean