Circadian rhythms are endogenic autonomous oscillators of physiological activities resulting from 24-hour day/night cycles. Circadian rhythms regulate a wide variety of metabolic and physiological functions. This allows the organism to control its molecular, biochemical, physiological, and behavioural processes. Some studies have recently been performed on the relationship between cancer and circadian rhythm. In this paper we analyse the relationship between pH, the Pentose Phosphate Pathway, and the circadian through two databases of RNA sequence, GSE101988 and GSE74439. It was found that the Period and Cryptochrome family genes, which are linked to DNA damage response pathways, are more expressed than the control groups. At the same time, CLOCK and BMAL genes were inhibited. This, therefore, forms our supposition that the pH, through several mechanisms, does affect the circadian and thus the tumour progression. This is a very important study focus, because acidosis and alkalosis could be a biomarker for early tumour apparition in local tissues. In this databased research, BMAL1 (BMAL2) was observed to be more active than the key circadian regulator at lower pH. Together, the CRY family of genes was downregulated in both datasets. However, in the analysis involving Pentose Phosphate Pathway inhibition, p53 was up-regulated and G6PD was without any statistically significant improvement.