The initial impact of the COVID-19 pandemic on the diagnosis of new cancers at a large pathology laboratory in the public health sector, Western Cape Province, South Africa.

BACKGROUND: The COVID-19 pandemic has disrupted cancer diagnostic services. A decline in the number of new cancers being diagnosed over a relatively short term implies a delay in diagnosis and subsequent treatment. This delay is expected to have a negative effect on cancerrelated morbidity and mortality. The impact of the pandemic on the number of new cancer diagnoses in our setting is unknown. OBJECTIVES: To assess the impact of COVID-19 on the number of new cancers diagnosed at our institution in the first 3 months following the implementation of lockdown restrictions, by focusing on common non-cutaneous cancers. METHODS: A retrospective laboratory-based audit was performed at a large anatomical pathology laboratory in Western Cape Province, South Africa. The numbers of new diagnoses for six common cancers (breast, prostate, cervix, large bowel, oesophagus and stomach) from 1 April 2020 to 30 June 2020 were compared with the corresponding period in 2019. RESULTS: Histopathological diagnoses for the six cancers combined decreased by 192 (-36.2%), from 531 new cases in the 2019 study period to 339 in the corresponding period in 2020. Substantial declines were seen for prostate (-58.2%), oesophageal (-44.1%), breast (-32.9%), gastric (-32.6%) and colorectal cancer (-29.2%). The smallest decline was seen in cervical cancer (-7%). New breast cancers diagnosed by cytopathology declined by 61.1%. CONCLUSIONS: The first wave of the COVID-19 pandemic and the associated response resulted in a substantial decline in the number of new cancer diagnoses, implying a delay in diagnosis. Cancer-related morbidity and mortality is expected to rise as a result, with the greatest increase in mortality expected from breast and colorectal cancer.

Ferritin assay performed on the Technicon Immuno 1 analyser using serum and plasma samples.

Ferritin assays were performed using both serum and plasma samples on the Bayer Technicon Immuno 1 Analyser and their ferritin test kit as only data for serum samples are available. After evaluation of the test kit and analyser the results were correlated using the Statistica for Windows programme. It was established that the plasma samples gave consistently lower values than the serum samples. Using the obtained conversion factor of 1.191, plasma as well as serum samples may be used for ferritin determinations.

Aberrations of curved zone plates and Fresnel lenses.

The generalization of zone plates and Fresnel lenses from the usual flat surfaces to curved surfaces is discussed. It is shown that, although Abbe's sine law applies to zone plates but not to Fresnel lenses, both can yield single-element aplanats if formed on a curved surface. Third-order aberration formulas are given.

Aberrations of a sequence of conic mirrors.

An interesting class of optical systems consists of conic mirrors arranged so that each mirror shares at least one focus with the optically adjacent mirrors. This paper presents simple results for several of the aberrations largely independent of the details of the configuration. Results are presented for sine law violation and third order astigmatism when the images are located at the focii of the mirrors and for astigmatism and distortion when the pupils are located at the foci. In both cases the system is equivalent to a single conic mirror having the same magnification and focal length. It is shown that there are configurations for which both the images and the pupils lie at foci, and for these all the above results apply. The exact shape of the image surface is obtained for such a system in which all the mirrors are parabolas.

Skew ray results for condensing light pipes and reflective baffles.

Simple criteria are presented for determining whether a general skew ray will strike an absorber at the exit of certain condensing light pipes. Several designs for ideal reflective baffles are also given and their skew ray properties discussed.