| Inclusion criteria |
Exclusion criteria |
| 1) Literature relevant to the role of a high-fat diet as a risk factor for breast cancer. |
1) The studies that did not discuss a high-fat diet as a risk factor for breast cancer were excluded because the study's objective was focused on the interrelationships between a high-fat diet and breast cancer. |
| 2) The studies must be original case-control studies, cohort studies, or randomized clinical controlled trials on the interplay of high-fat diet and breast cancer. |
2) Opinion pieces, review articles, non-scholarly articles, secondary studies, scoping reviews, and research approaches other than primary studies were excluded. |
| 3) The selected studies may be heterogenous but must have measurable endpoints with calculatable risks like hazard ratio (HR), odd ratio (OR), or relative risk (RR). |
3) Studies without calculatable risks - odd ratio (OR), hazard ratio (HR), or relative risk (RR) were excluded. |
| 4) Human studies. |
4) Animal studies. |
| 5) The studies must be published in a peer-reviewed journal to maintain the validity and reliability of the studies. |
5) The studies that were published in non-peer-reviewed journals, and dissertations were excluded. |
| 6) The studies must be originally published in English for readability by the reviewers. |
6) The studies originally published in a language other than English were discarded. |
| 7) Works of literature published between (2010–2020). |
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