Cancer is considered one of the main causes of death worldwide. A combination of various genetic or epigenetic modifications, which lead to distinct chromosomal abnormalities or mutations, cause somatic cell transformations to cancer cells. Since tumour progression is caused by multiple mechanisms and factors, estimating the risk of cancer and determining the appropriate therapy are both becoming serious challenges. Ultimately, a fundamental aim is to design targeted therapeutics to treat cancer without the limitation of potential adverse side effects on normal cells. The identification and functional characterisation of specific genes, which are known as cancer testis antigens (CTAs) gene or cancer/germline genes provides a number of cancer-specific biomarkers. Their expression is largely limited to germline cells in normal tissues, and can play a core role in cancer diagnosis, prognosis, prevention and treatment. In this study, a novel human CTA gene, SPO11, is identified in terms of its expression, protein localisation and likely function in different cancer cells. Herein, we demonstrate that human SPO11 protein is observed in testis, most cancer cells, and some tumour tissues, but it is not found in normal healthy tissues. SPO11 knockdown in various cancer cell lines results in reduced proliferation, detached and unviable cells. We present evidence to suggest that SPO11 depletion alters the level of cell cycle regulatory proteins without inducing apoptosis or senescence, suggesting SPO11 functions in cancer cells to alter cell cycle dynamics. Since chromosomal instability and uncontrolled cell proliferation are considered hallmarks of human cancer, the results presented herein suggest that SPO11 may play a critical role in genome stability control and be essential for cancer progression. The presence of SPO11 in cancer cells may lead to aberrant initiation of DNA double-stranded breaks and/or altered DNA replication/chromosome segregation during mitosis resulting in chromosome changes that subsequently develop towards cancer. Eventually, the SPO11 protein may have diagnostic, prognostic and therapeutic value in cancer treatment.